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Background The incidence of kidney transplantation performed in elderly patients has increased steadily recently. Higher risk of infection and mortality, but lower rate of rejection, are reported in older kidney transplant patients. This study aims to analyze the effect of transplantation on aging of T and B cells in kidney transplant patients, with the emphasis on age and Cytomegalovirus (CMV) latency. Results We included 36 patients before and after (median 2.7 years) kidney transplantation and 27 age- and sex-matched healthy controls (HC). T and B cell subsets were measured by flow cytometry, with a focus on aged T cells (CD28-), and age associated B cells (ABCs, CD19 + CD21-CD11c+). Three years after transplantation a significant increase of total T cells among the lymphocytes was found compared to pre-transplantation and HC. Among the T cells CD4+ cells were decreased, especially naïve CD4+ cells and regulatory T cells. Total CD8+ cell proportions were increased, and proportions of naïve CD8+ cells were significantly decreased after transplantation, while CD8+ effector memory T cells re-expressing CD45RA were increased. CD28− T cells were significantly higher compared to HC after transplantation, especially in CMV seropositive patients. B cells were significantly decreased, while among B cells memory B cells and especially ABCs were increased after transplantation. Conclusions After transplantation T and B cell subsets change towards more terminally differentiated memory cells compared to age-matched HC. Proportions of aged T cells and ABCs were associated with CMV serostatus.

Autoreactive B cells are key drivers of pathogenic processes in autoimmune diseases by the production of autoantibodies, secretion of cytokines, and presentation of autoantigens to T cells. However, the mechanisms that underlie the development of autoreactive B cells are not well understood. Here, we review recent studies leveraging novel techniques to identify and characterize (auto)antigen-specific B cells. The insights gained from such studies pertaining to the mechanisms involved in the escape of tolerance checkpoints and the activation of autoreactive B cells are discussed. In addition, we briefly highlight potential therapeutic strategies to target and eliminate autoreactive B cells in autoimmune diseases.

This narrative review focuses on the herpes zoster (HZ) and its prevention in transplant patients. Varicella zoster virus (VZV) is highly contagious and distributed worldwide in humans. Primary VZV infection usually causes varicella and then establishes a lifelong latency in dorsal root ganglia. Reactivation of VZV leads to HZ and related complications such as postherpetic neuralgia. Age and decreased immunity against VZV are important risk factors for developing HZ. Transplant patients are at increased risk for developing HZ and related complications due to their immunocompromised status and the need for lifetime immunosuppression. Diagnosis of HZ in transplant patients is often clinically difficult, and VZV-specific antibodies should be determined by serologic testing to document prior exposure to VZV during their pre-transplant evaluation process. Although antiviral agents are available, vaccination should be recommended for preventing HZ in transplant patients considering their complicated condition and weak organ function. Currently, there are two licensed HZ vaccines, of which one is a live-attenuated vaccine and the other is a HZ subunit vaccine. Both vaccines have shown promising safety and efficacy in transplants patients and especially the subunit vaccine could be administered post-transplant since this vaccine does not contain any live virus. Larger studies are needed about safety and immunogenicity of HZ vaccines in transplant populations, and extra efforts are needed to increase vaccine usage according to guidelines.

Giant cell arteritis (GCA) is an autoimmune vasculitis affecting large and medium-sized arteries. Ample evidence indicates that GCA is a heterogeneous disease in terms of symptoms, immune pathology, and response to treatment. In the current review, we discuss the evidence for disease subsets in GCA. We describe clinical and immunologic characteristics that may impact the risk of cranial ischemic symptoms, relapse rates, and long-term glucocorticoid requirements in patients with GCA. In addition, we discuss both proven and putative immunologic targets for therapy in patients with GCA who have an unfavorable prognosis. Finally, we provide recommendations for further research on disease subsets in GCA.

In this study, we sought to understand the selective pressures shaping the Ig-producing cell repertoire in the parotid glands of primary Sjögren’s syndrome (pSS) patients before and after rituximab treatment (RTX). In particular, we evaluated the role of potential N-glycosylation motifs acquired by somatic hypermutation (ac-Nglycs) within Ig H chain V region (IGHV) genes as alternative selective pressures for B cells in pSS. Five pSS patients received RTX. Sequential parotid salivary gland biopsies were taken before RTX, at 12 wk and at 36–52 wk after treatment. Parotid biopsies from four non-pSS patients served as controls. Sequence analysis was carried out on the IgA and IgG RNA transcripts expressing IGHV3 genes in all parotid biopsies. Both IgG and IgA sequences from pSS patients exhibited no evidence for positive Ag-driven selection pressure in their CDRs in contrast to non-pSS controls. The prevalence of IgG sequences with ac-Nglycs was significantly higher in pSS patients than in non-pSS controls. Selection pressures shaping the IgG and IgA repertoire within pSS patients’ parotid glands are distinct from those in non-pSS controls, with very little evidence for positive (auto)antigen selection. The higher prevalence of ac-Nglycs on pSS-IgG compared with non-pSS IgG indicates that ac-Nglycs could be an alternative form of selection pressure. We speculate that B cell hyperproliferation within parotid glands of pSS patients may result from Ag-independent interactions such as that between glycosylated B cell receptors and lectins within the microenvironment rather than (auto)antigen-specific stimulation. Our study brings a new perspective into research on pSS.

Introduction. Herpes zoster, which can have a major impact on quality of life, results from reactivation of a latent varicella-zoster virus (VZV) infection. We hypothesized that giant cell arteritis (GCA) patients are at increased risk of herpes zoster because of treatment with high-dose glucocorticoids and advanced age. Aim of the study therefore was to determine cell-mediated and humoral immunity to VZV in patients with GCA, patients with closely related disease polymyalgia rheumatica (PMR; treated with lower doses of glucocorticoids) and healthy controls. Methods. Cell-mediated immunity to VZV was determined by performing interferon-γ (IFNγ) enzyme-linked immunospot (ELISpot) and intracellular cytokine flow cytometry measurements in 11 GCA and 15 PMR patients, and in 26 age/sex-matched healthy controls. Immunoglobulin G antibodies to VZV glycoprotein (VZV-IgG) were measured in serum samples of 35 GCA and 26 PMR patients at different times of follow-up, and in 58 age and sex matched healthy controls by an enzyme-linked immunosorbent assay (ELISA). Results. The number of VZV-specific IFNγ spot-forming cells was significantly lower in GCA patients on treatment, than in age-matched healthy controls (p=0.029), but was not different in PMR patients on treatment. Similar levels of VZV-IgG were found in GCA and PMR patients at baseline, compared to healthy controls. Conclusion. The finding of a decreased cell-mediated immunity to VZV, known to be of great importance in defense to the virus, indicates an increased herpes zoster risk in GCA patients compared to an already at-risk elderly population. Herpes zoster vaccination is therefore of special importance in GCA patients, and would ideally be administered at time of diagnosis. Interestingly, as VZV was suggested to be the trigger in GCA pathogenesis, similar levels of VZV-IgG were found in GCA patients at time of diagnosis and age matched healthy controls, indicating that GCA patients did not experience herpes zoster substantially more often in the months preceding diagnosis than controls.

Background Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are strongly overlapping diseases that are thought to have a shared etiology [1]. The observation of varicella-zoster virus (VZV) antigen in temporal artery biopsies of GCA patients led to the hypothesis that VZV might be a trigger for the onset of the disease [2]. Herpes zoster occurs when the latently present VZV reactivates. It has been reported that patients with GCA do not appear to be at increased risk of herpes zoster compared with age and sex matched controls, even during treatment with high dose glucocorticoids [3]. Levels of VZV specific immunoglobulin G (VZV-IgG) are known to only slowly decline again after a reactivation [4]. We therefore hypothesized, in line with the proposed etiologic role, to find higher VZV-IgG levels in GCA and PMR patients at disease onset, compared to healthy controls. Furthermore, we expected to find no differences in cell-mediated immunity to the virus between patients and controls assuming that the incidence of herpes zoster is not increased in GCA. Objectives To investigate humoral and cellular immunity to VZV in GCA and PMR patients and compare these to results in age-and sex matched healthy controls. Methods Antibody responses to VZV glycoprotein were measured in serum samples of 35 GCA patients and 26 PMR patients at baseline (before glucocorticoid treatment) and during follow up, and in 58 healthy controls by an enzyme-linked immunosorbent assay (ELISA). Cell-mediated immunity to VZV was determined by performing interferon-γ (IFNγ) enzyme-linked immunosorbent spot (ELISpot) and intracellular cytokine flow cytometry measurements in 11 GCA patients and 15 PMR patients, and in 26 age and sex matched healthy controls. Results Similar levels of VZV-IgG were found in GCA and PMR patients at baseline, and healthy controls. The number of VZV specific IFNγ spot-forming cells was significantly lower in GCA patients than in healthy controls (p=0.029), but not different in PMR patients compared to healthy controls. Conclusions Since antibody levels at baseline were not different in GCA and PMR patients compared to healthy controls it seems unlikely that VZV has an important role in the aetiology of GCA or PMR. The finding of a decreased cell-mediated immunity in GCA patients, especially after treatment with high dose corticosteroids may indicate an increased risk of developing herpes zoster. References Buttgereit F, Dejaco C, Matteson EL, Dasgupta B. Polymyalgia Rheumatica and Giant Cell Arteritis: A Systematic Review. Jama 2016 Jun 14;315(22):2442–2458. Gilden D, Nagel MA. Varicella zoster virus and giant cell arteritis. Current opinion in infectious diseases 2016 Jun;29(3):275–279. Schafer VS, Kermani TA, Crowson CS, Hunder GG, Gabriel SE, Ytterberg SR, et al. Incidence of herpes zoster in patients with giant cell arteritis: a population-based cohort study. Rheumatology (Oxford, England) 2010 Nov;49(11):2104–2108. Cradock-Watson JE, Ridehalgh MK, Bourne MS. Specific immunoglobulin responses after varicella and herpes zoster. The Journal of hygiene 1979 Apr;82(2):319–336. Disclosure of Interest None declared

Objective Patients with autoimmune diseases such as systemic lupus erythematosus (SLE) and granulomatosis with polyangiitis (Wegener's) (GPA) have a 3–20-fold increased risk of herpes zoster compared to the general population. The aim of this study was to evaluate if susceptibility is due to decreased levels of cellular and/or humoral immunity to the varicella-zoster virus (VZV). Methods A cross-sectional study of VZV-specific immunity was performed in 38 SLE patients, 33 GPA patients, and 51 healthy controls. Levels of IgG and IgM antibodies to VZV were measured using an in-house glycoprotein enzyme-linked immunosorbent assay (ELISA). Cellular responses to VZV were determined by interferon-γ (IFNγ) enzyme-linked immunospot (ELISpot) assay and carboxyfluorescein succinimidyl ester (CFSE) dye dilution proliferation assay. Results Levels of IgG antibodies to VZV were increased in SLE patients as compared to healthy controls, but levels of IgM antibodies to VZV were not. Antibody levels in GPA patients did not differ significantly from levels in healthy controls. In response to stimulation with VZV, decreased numbers of IFNγ spot-forming cells were found among SLE patients (although not GPA patients) as compared to healthy controls. Proliferation of CD4+ T cells in response to stimulation with VZV was decreased in SLE patients but not GPA patients. Conclusion SLE patients have increased levels of IgG antibodies against VZV, while cellular immunity is decreased. In GPA patients, antibody levels as well as cellular responses to VZV were comparable to those in healthy controls. These data suggest that increased prevalence of herpes zoster in SLE patients is due to a poor cellular response. Vaccination strategies should aim to boost cellular immunity against VZV.

Objective Several lines of evidence indicate that B cells may be involved in the immunopathology of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR). This study was undertaken to examine the distribution of defined B cell subsets, including effector B (Beff) cells and regulatory B (Breg) cells, in patients with GCA and patients with PMR before and after corticosteroid treatment. Methods Circulating B cells were analyzed in 34 newly diagnosed, untreated patients with GCA or PMR, and in 44 followup samples from patients with GCA or PMR who received corticosteroids for 2 weeks or 3 months. For comparison, 40 age-matched healthy controls and 11 rheumatoid arthritis (RA) patients were included. Serum BAFF levels were determined, and temporal arteries were studied by immunohistochemistry. Results Patients newly diagnosed as having GCA or PMR, but not patients with RA, had decreased numbers of circulating B cells compared to healthy controls. B cell numbers recovered rapidly in treated patients with GCA and PMR in remission. This recovery was not achieved by compensatory hyperproliferation or enhanced bone marrow production. B cell numbers inversely correlated with erythrocyte sedimentation rates, C-reactive protein levels, and serum BAFF levels. Tumor necrosis factor α–positive Beff cells, but not interleukin-10 (IL-10)–positive Breg cells, were decreased in patients newly diagnosed as having GCA or PMR. Following treatment, circulating numbers of Beff cells normalized. The returning Beff cells demonstrated an enhanced capacity to produce IL-6. Few B cells were found in temporal artery biopsy specimens from GCA patients. Conclusion We show for the first time that the distribution of B cells is highly disturbed in GCA and PMR and that B cells likely contribute to the enhanced IL-6 response in both diseases.

Primary Sjögren's syndrome (pSS) is characterized by mononuclear inflammatory infiltrates and IgG plasma cells in salivary and lacrimal glands which lead to irreversible destruction of the glandular tissue and is accompanied by sensation of dryness of mouth and eyes. B cells play a central role in the immunopathogenesis and exhibit signs of hyperactivity. Hyperactivity of B cells is the consequence of the coordinated and integrated action of stimulation of the B-cell receptor, CD40 and toll-like receptors in the presence of appropriate cytokines. As discussed, overexpression of type I IFN and BAFF on one hand and IL-6 and IL-21 on the other hand are critically involved in the enhanced plasma cell formation in pSS patients. Hyperactivity of B cells results in secretion of autoantibodies and production of various cytokines. These insights in the role of B cells in the pathogenetic process of pSS offer ample targets for successful therapeutical intervention in pSS.

Previous studies in rodents have indicated that only a minor fraction of the immunoglobulin heavy chain variable region (IGHV-Cμ) transcripts carry somatic mutations and are considered memory B cells. This is in marked contrast to humans where nearly all marginal zone B (MZ-B) cells are mutated. Here we show in rats that the proportion of mutated IgM+ MZ-B cells varies significantly between the various IGHV genes analyzed, ranging from 27% mutated IGHV5 transcripts to 65% mutated IGHV4 transcripts. The observed data on mutated sequences in clonally-related B cells with a MZ-B cell or follicular B (FO-B) cell phenotype indicates that mutated IgM+ MZ-B and FO-B cells have a common origin. To further investigate the origin of mutated IgM+ MZ-B cells we determined whether mutations occurred in rearranged IGHV-Cμ transcripts using IGHV4 and IGHV5 genes from neonatal rat MZ-B cells and FO-B cells. We were not able to detect mutations in any of the IGHV4 and IGHV5 genes expressed by MZ-B cells or FO-B cells obtained from neonatal rat spleens. Germinal centres (GCs) are absent from neonatal rat spleen in the first few weeks of their life, and no mutations were found in any of the neonatal sequences, not even in the IGHV4 gene family which accumulates the highest number of mutated sequences (66%) in the adult rat. Therefore, these data do not support the notion that MZ-B cells in rats mutate their IGHV genes as part of their developmental program, but are consistent with the notion that mutated rat MZ-B cells require GCs for their generation. Our findings support that the splenic MZ of rats harbors a significant number of memory type IgM+ MZ-B cells with mutated IGHV genes and propose that these memory MZ-B cells are probably generated as a result of an antigen driven immune response in GCs, which still remains to be proven.

Background It remains controversial whether avoidance of dietary diabetogenic triggers, such as cow's milk proteins, can prevent type 1 diabetes in genetically susceptible individuals. Here, different extensive casein hydrolysates (HC) and single amino acid (AA) formulations were tested for their effect on mechanisms underlying autoimmune diabetes pathogenesis in diabetes-prone BioBreeding rats. Intestinal integrity, gut microbiota composition and mucosal immune reactivity were studies to assess whether these formulations have differential effects in autoimmune diabetes prevention. Methods Diabetes-prone BioBreeding rats received diets in which the protein fraction was exchanged for the different hydrolysates or AA compositions, starting from weaning until the end of the experiment (d150). Diabetes development was monitored, and faecal and ileal samples were collected. Gut microbiota composition and cytokine/tight junction mRNA expression were measured by quantitative polymerase chain reaction. Cytokine levels of ileum explant cultures were measured by ELISA, and intestinal permeability was measured in vivo by lactulose-mannitol assay. Results Both HC-diet fed groups revealed remarkable reduction of diabetes incidence with the most pronounced effect in Nutramigen (R)-fed animals. Interestingly, AA-fed rats only showed delayed autoimmune diabetes development. Furthermore, both HC-fed groups had improved intestinal barrier function when compared with control chow or AA-fed animals. Interestingly, higher IL-10 levels were measured in ileum tissue explants from Nutramigen (R)-fed rats. Beneficial gut microbiota changes (increased Lactobacilli and reduced Bacteroides spp. levels) were found associated especially with HC-diet interventions. Conclusions Casein hydrolysates were found superior to AA-mix in autoimmune diabetes prevention. This suggests the presence of specific peptides that beneficially affect mechanisms that may play a critical role in autoimmune diabetes pathogenesis. Copyright (c) 2012 John Wiley & Sons, Ltd.

Anti-helminth immunity involves CD4(+) T cells, yet the precise effector mechanisms responsible for parasite killing or expulsion remain elusive. We now report an essential role for antibodies in mediating immunity against the enteric helminth Heligmosomoides polygyrus (Hp), a natural murine parasite that establishes chronic infection. Polyclonal IgG antibodies, present in naive mice and produced following Hp infection, functioned to limit egg production by adult parasites. Comparatively, affinity-matured parasite-specific IgG and IgA antibodies that developed only after multiple infections were required to prevent adult worm development. These data reveal complementary roles for polyclonal and affinity-matured parasite-specific antibodies in preventing enteric helminth infection by limiting parasite fecundity and providing immune protection against reinfection, respectively. We propose that parasite-induced polyclonal antibodies play a dual role, whereby the parasite is allowed to establish chronicity, while parasite load and spread are limited, likely reflecting the long coevolution of helminth parasites with their hosts.

Background: Both the role of inducible nitric oxide synthase (iNOS) in the development of inflammatory bowel disease (IBD) as well as the molecular details governing its mucosal induction remain unclear. Methods: In the present study we evaluated the role of the residing intestinal microflora in the induction of epithelial iNOS upon transfer of CD45RB(high) CD4(+) T cells to SCID mice. CB-17 SCID mice were reared with conventional flora (CNV) or germfree CB-17 SCID mice were monoassociated with Helicobacter muridarum, act A(-) mutant Listeria monocytogenes, segmented filamentous bacteria (SFB), or Ochrobactrum anthropi. Results: Within 2 weeks CNV SCID mice injected with CD45RB high CD4+ T cells showed a focal, epithelial iNOS expression on the apical site of villi that preceded the infiltration of CD4(+) T cells and cytokine production followed by extension of this expression to the entire surface along the whole crypt axis as the colitis progressed. SCID mice monoassociated with H. muridarum developed a severe colitis and showed high epithelial iNOS expression. CNV-SCID mice without T cells and SCID mice monoassociated with SFB did not show any iNOS expression, whereas SCID mice monoassociated with act A(-) mutant L. monocytogenes and O. anthropi showed some scattered epithelial iNOS staining on the apical site of a few villi, but none of these mice developed colitis. Conclusions: These findings demonstrate that the expression of epithelial iNOS is highly bacterium-specific and correlates with the severity of disease, suggesting an important role for this enzyme in the development of IBD.

Unique gas and liquid phase radioactive tracer experiments have been performed in horizontal cross-flow bubble column reactors of a commercial ethylbenzene oxidation plant. These experiments validated CFD modelling predictions, which in turn formed the basis for evaluation and selection of potential measures to reduce “oxygen starvation” predicted to occur for certain configurations and operating conditions. After implementation in commercial reactors lower operating temperatures, improved selectivity and thus better plant yields were achieved.

Multiple Myeloma ( MM) is a plasma cell malignancy which is characterized by a very heterogeneous disease outcome. Heterogeneity in plasma cell characteristics, including morphology, maturation status, immunophenotype and genetic abnormalities partly account for the variable disease outcome. Although the plasma cell is the predominant cell type in MM, several studies have shown that less mature B cells, which are clonally related to the malignant plasma cells, are present in the bone marrow and peripheral blood of MM patients. The significance of these so-called myeloma clonotypic B cells in the disease process remains largely unknown. In this review the role of myeloma clonotypic B cells and myeloma tumor clone heterogeneity in relation to prognosis and clinical outcome are discussed.

Primary plasma cell leukaemia (PCL) is a rare plasma cell malignancy, which is related to multiple myeloma (MM) and is characterized by a poor prognosis. In a previous study we demonstrated that PCL plasma cells display a high expression of CD27, in contrast to MM plasma cells. The present study was set out to assess the functional properties of CD27 expressed on PCL plasma cells by triggering with its ligand CD70. Using CD27-expressing purified plasma cells from a PCL patient we demonstrated that CD27-triggering modestly inhibited spontaneous and dexamethasone-induced apoptosis. In vitro stimulation and Western blotting showed that activation of p38 and extracellular-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinases (MAPK) was associated with CD27-mediated signal transduction. Specific inhibition of p38 and ERK1/2 MAPK abolished the anti-apoptotic effects of CD27-triggering. Interestingly, simultaneous inhibition of p38 and ERK1/2 strongly sensitized PCL cells for dexamethasone-induced apoptosis. Finally, in dexamethasone-treated PCL cells, CD27-triggering was associated with persistent DNA-binding activity of activator protein 1 (AP-1) but not of nuclear factor-kappaB. These findings suggest that, in primary PCL, specific anti-apoptotic pathways exist that might provide novel therapeutic targets.

Expression of CD27 on malignant plasma cells (PC) (CD138+CD38++) was analysed in a cross-sectional study of bone marrow (BM) samples from multiple myeloma (MM) patients (n = 28), monoclonal gammopathy of undetermined significance (MGUS) patients (n = 6) and BM PC from healthy donors (n = 4). MM PC expressed CD27 with a variable, lower intensity pattern compared with the consistent high expression in MGUS and healthy donors. MM patients in complete clinical remission displayed a higher percentage of CD27+ PC compared with patients at diagnosis, relapse or in partial remission. In MM, loss of CD27 correlated with loss of CD19 (R2 = 0.4, P < 0.0001). Human MM cell lines (n = 9) did not express CD27 whereas de novo plasma cell leukaemia (PCL) (n = 3) had a high expression. Re-analysis of a cDNA microarray data set, generated from newly diagnosed MM patients (n = 74), demonstrated that the MM subgroup with the highest prevalence of poor prognostic factors had the lowest CD27 mRNA expression. Fluorescence-activated cell sorting and allele-specific oligonucleotide polymerase chain reaction showed that both CD27+ and CD27- PC subpopulations in MM can belong to the clonal disorder. In conclusion, CD27 is heterogeneously expressed on MM PC and loss of CD27 expression might have prognostic value in MM.

Total genomic DNA from samples of intact mouse small intestine, large intestine, caecum and faeces was used as template for PCR amplification of 16S rRNA gene sequences with conserved bacterial primers. Phylogenetic analysis of the amplification products revealed 40 unique 16S rDNA sequences. Of these sequences, 25% (10/40) corresponded to described intestinal organisms of the mouse, including Lactobacillus spp., Helicobacter spp., segmented filamentous bacteria and members of the altered Schaedler flora (ASF360, ASF361, ASF502 and ASF519); 75% (30/40) represented novel sequences. A large number (11/40) of the novel sequences revealed a new operational taxonomic unit (OTU) belonging to the Cytophaga–Flavobacter–Bacteroides phylum, which the authors named ‘mouse intestinal bacteria’. 16S rRNA probes were developed for this new OTU. Upon analysis of the novel sequences, eight were found to cluster within the Eubacterium rectale–Clostridium coccoides group and three clustered within the Bacteroides group. One of the novel sequences was distantly related to Verrucomicrobium spinosum and one was distantly related to Bacillus mycoides. Oligonucleotide probes specific for the 16S rRNA of these novel clones were generated. Using a combination of four previously described and four newly designed probes, approximately 80% of bacteria recovered from the murine large intestine and 71% of bacteria recovered from the murine caecum could be identified by fluorescence in situ hybridization (FISH).

Summary. In the peripheral blood (PB) of multiple myeloma (MM) patients, clonotypic B cells are present that express the identical V(D)J rearrangements as the malignant plasma cells in the bone marrow. In the present study, the proliferative capacity of clonotypic B cells from MM patients (n = 10) and the ability to differentiate in vitro was determined using the CD40-culturing system. For six patients, the presence of clonotypic B cells expressing variant immunoglobulin (Ig) isotypes was assessed by Ig isotype-specific allele-specific oligonucleotide reverse transcription polymerase chain reaction (ASO-RT-PCR) after culturing with CD40L and interleukin 4 (IL-4). In three out of six patients, clonotypic B cells expressing variant isotypes were detected both before and after culturing. The ability of clonotypic B cells to undergo B-cell differentiation was studied by abrogating CD40 signalling accompanied by IL-10 and IL-2 stimulation, enhancing differentiation towards Ig-secreting cells. The numbers of clonotypic B cells were determined by quantitative ASO-PCR. An increase in cell number was observed upon CD40L and IL-4 stimulation, whereas the relative number of clonotypic B cells was unaltered. In contrast, upon B-cell differentiation the relative number of clonotypic B cells decreased. In conclusion, clonotypic B cells can be cultured and isolated in vitro using the CD40 system. Clonotypic B cells responded to CD40 triggering in a similar fashion as to non-clonotypic normal B cells. However, the ability of clonotypic B cells to undergo in vitro activation and differentiation into Ig-secreting cells is hampered.

The plasma cell proliferative disorders monoclonal gammopathy of undetermined significance (MGUS) and malignant multiple myeloma (MM) are characterized by an accumulation of transformed clonal plasma cells in the bone marrow and production of monoclonal immunoglobulin. They typically affect an older population, with median age of diagnosis of approximately 70 years. In both disorders, there is an increased risk of infection due to the immunosuppressive effects of disease and conjointly of therapy in MM, and response to vaccination to counter infection is compromised. The underlying factors in a weakened immune response in MGUS and MM are as yet not fully understood. A confounding factor is the onset of normal aging, which quantitatively and qualitatively hampers humoral immunity to affect response to infection and vaccination. In this review, we examine the status of immune alterations in MGUS and MM and set these against normal aging immune responses. We focus primarily on quantitative and functional aspects of B-cell immunity. Furthermore, we review the current knowledge relating to susceptibility to infectious disease in MGUS and MM, and how efficacy of conventional vaccination is affected by proliferative disease-related and therapy-related factors.

Kabat's database has often been used to design mouse Vh gene-specific 5 ' primers. The emphasis was mostly on constructing a universal (degenerate) 5 ' primer or 5 ' primer set, which would be able to match every mouse Vh gene. We were interested in finding oligonucleotides that could be used as primers or probes that can discriminate between the different Vh gene families. To this end, Kabat's database was reordered into Vh gene families based on more than 80% homology to prototype Vh gene family sequences. Rules were formulated for adequate annealing of putative primers to their respective genes. Putative primers were derived from the consensus sequences of the Vh gene families. A computer program was designed to systematically screen for the most optimal 5 ' and 3 ' Vh gene family-specific primers. This program enabled us to find a set of framework I-specific 5 ' primers, as well as a set of framework III-specific 3 ' primers. The found primers were also tested for their use as Vh gene family-specific probes. (C) 2001 Elsevier Science B.V. All rights reserved.

Brown-Norway (BN) and Dorus Zadel Black (DZB) rats develop a T-cell-dependent membranous glomerulopathy (MGP) with high proteinuria and antiglomerular basement membrane (GBM) autoreactive antibodies (Abs), upon exposure to mercuric chloride (HgCl2). Laminin is an important autoantigenic target of the anti-GBM Abs, absorbing approximate to 30% of the anti-GBM reactivity. Although many anti-GBM Abs have undergone isotype switching, it is currently unclear whether affinity maturation occurs during the HgCl2-induced autoimmune response. To address this question we analyzed the rearranged immunoglobulin heavy chain variable-region genes (V(H)DJ(H) regions) of 15 mAbs that were previously obtained from HgCl2-treated rats. Seven of these mAbs exhibit reactivity towards laminin. Our study showed that the V-H-gene usage of antilaminin mAbs is largely restricted to the PC7183 V-H-gene family (six out of seven). In addition, we demonstrated that at least three out of six laminin reactive and five out of six non-laminin-binding mAbs are encoded by germline V-H genes (a total of eight out of 12 mAbs). Of the eight mAbs that are encoded by germline V-H genes, seven are of a non-immunoglobulin M (IgM) isotype, indicating that isotype switching has occurred in these mAbs in the absence of somatic mutations. The mutations observed in the V-H genes of the four remaining mAbs do not provide strong evidence for antigenic selection. The data support the notion that B cells in this model of MGP are not subjected to affinity maturation and probably result from polyclonal B-cell activation.

Patients with autoimmune diseases such as systemic lupus erythematosus (SLE) and granulomatosis with polyangiitis (Wegener's) (GPA) have a 3-20-fold increased risk of herpes zoster compared to the general population. The aim of this study was to evaluate if susceptibility is due to decreased levels of cellular and/or humoral immunity to the varicella-zoster virus (VZV).A cross-sectional study of VZV-specific immunity was performed in 38 SLE patients, 33 GPA patients, and 51 healthy controls. Levels of IgG and IgM antibodies to VZV were measured using an in-house glycoprotein enzyme-linked immunosorbent assay (ELISA). Cellular responses to VZV were determined by interferon-γ (IFNγ) enzyme-linked immunospot (ELISpot) assay and carboxyfluorescein succinimidyl ester (CFSE) dye dilution proliferation assay.Levels of IgG antibodies to VZV were increased in SLE patients as compared to healthy controls, but levels of IgM antibodies to VZV were not. Antibody levels in GPA patients did not differ significantly from levels in healthy controls. In response to stimulation with VZV, decreased numbers of IFNγ spot-forming cells were found among SLE patients (although not GPA patients) as compared to healthy controls. Proliferation of CD4+ T cells in response to stimulation with VZV was decreased in SLE patients but not GPA patients.SLE patients have increased levels of IgG antibodies against VZV, while cellular immunity is decreased. In GPA patients, antibody levels as well as cellular responses to VZV were comparable to those in healthy controls. These data suggest that increased prevalence of herpes zoster in SLE patients is due to a poor cellular response. Vaccination strategies should aim to boost cellular immunity against VZV.

Background: Autoimmune mechanisms are postulated to play a role in the development and progression of Wegener's granulomatosis (WG), a form of systemic, idiopathic necrotizing vasculitis,Objective: We investigated the relation between lymphocyte activation and disease activity in patients with WG, Methods: B- and T-lymphocyte activation was studied by cytometric assessment of the expression of the activation markers CD38 on B cells and CD25 and HLA-DR on CD4(+) and CD8(+) T-cell subsets, respectively. Activation at the cellular level was related to serum levels of antineutrophil cytoplasmic antibodies and soluble IL-2 receptor, which can be regarded as soluble activation markers of B and T cells.Results: Percentages of CD38(bright) activated B cells were higher in patients with active WG than in patients experiencing disease remission (P Conclusion: In WG, B-cell activation is related to active disease, whereas T-cell activation persists during remission of the disease, which points to an intrinsic disordered immune system in this disease.

A high incidence of oligoclonal serum M-components is observed in multiple myeloma (MM) patients treated with autologous stem cell transplantation (ASCT). To determine whether these M-components are produced by myeloma clonally related cells or caused by an aberrant B-cell regeneration we analysed by semi-nested ASO-RT-PCR and DNA sequencing the immunoglobulin (Ig) variable genes (VH) obtained from bone marrow samples obtained before and after transplantation and peripheral blood stem cell (PBSC) samples from seven patients. Myeloma clonally related cells are identifiable by the expression of variant Ig heavy chain isotypes and were detected in two patients at presentation. No myeloma clonally related cells were found in post-transplantation samples (n = 7) in spite of the appearance of new serum M-components. However, in two cases we amplified sequences from post-transplantation bone marrow cells that were able to bind to the B-cell clone-specific CDR3 oligonucleotides but showed no further similarity regarding the VDJ rearrangement. These data indicate that serum oligoclonality post-transplantation is not caused by myeloma clonally related B cells but rather by the regenerating B-cell compartment.

Next to conventional B cells (or B-2 cells), peritoneal B-1 cells have been shown to contribute significantly to the production of IgA-secreting plasma cells in the gut. Evidence for this was mainly based on studies comprising manipulated animals, including lethally X-irradiated and transgenic mice. To examine the ability of peritoneal B-1 cells from untreated mice to switch actively to IgAin vivo, we performed RT-PCR analysis on FACS-sorted peritoneal B-cell subsets from untreated BALB/c mice in order to examine the presence of germline CαmRNA and mature CαmRNA transcripts. Germline Cαand mature Cαtranscripts were readily detectable in peritoneal B-1 cells (defined as IgMbright/IgDdull), but not, or very little, in peritoneal B-2 cells (defined as IgMdull/IgDbright). Moreover, by subdividing the B-l-cell population in CD5+B-1a cells and CD5-B-1b cells, it was shown thatin vivoexpression of germline Cαand mature Cαtranscripts was largely restricted to the B-1b-cell lineage. These results indicate that peritoneal B-1 cells indeed are capable to switch to IgA under normal physiological conditions and hereby further support the view that B-1 cells contribute significantly to the mucosal IgA response, albeit this function appears to be restricted to the B-1b-cell subset.

Several lines of evidence indicate that B cells may be involved in the immunopathology of giant cell arteritis (GCA) and polymyalgia rheumatica (PMR). This study was undertaken to examine the distribution of defined B cell subsets, including effector B (Beff) cells and regulatory B (Breg) cells, in patients with GCA and patients with PMR before and after corticosteroid treatment.Circulating B cells were analyzed in 34 newly diagnosed, untreated patients with GCA or PMR, and in 44 followup samples from patients with GCA or PMR who received corticosteroids for 2 weeks or 3 months. For comparison, 40 age-matched healthy controls and 11 rheumatoid arthritis (RA) patients were included. Serum BAFF levels were determined, and temporal arteries were studied by immunohistochemistry.Patients newly diagnosed as having GCA or PMR, but not patients with RA, had decreased numbers of circulating B cells compared to healthy controls. B cell numbers recovered rapidly in treated patients with GCA and PMR in remission. This recovery was not achieved by compensatory hyperproliferation or enhanced bone marrow production. B cell numbers inversely correlated with erythrocyte sedimentation rates, C-reactive protein levels, and serum BAFF levels. Tumor necrosis factor α-positive Beff cells, but not interleukin-10 (IL-10)-positive Breg cells, were decreased in patients newly diagnosed as having GCA or PMR. Following treatment, circulating numbers of Beff cells normalized. The returning Beff cells demonstrated an enhanced capacity to produce IL-6. Few B cells were found in temporal artery biopsy specimens from GCA patients.We show for the first time that the distribution of B cells is highly disturbed in GCA and PMR and that B cells likely contribute to the enhanced IL-6 response in both diseases.

Human peripheral blood leukocyte (PBL) reconstitution of severe combined immunodeficient (SCID) mice has provided a small animal model system (hu-PBL-SCID) useful for the study of the human immune system and disease pathogenesis. Transfer of xenogeneic PBL from donors other than humans has also been successful; however, the controversy remains regarding the capability of xenogeneically engrafted lymphocytes to mount a primary immune response. Human cells have been identified in offspring from hu-PBL-SCID but were not evaluated for a primary immune response. In the present study, offspring of bovine PBL-reconstituted SCID mice (F1-PBL-SCID-bo) were assessed for specific immune function. Sera from all of the F1-PBL-SCID-bo contained relatively low levels of bovine IgG 5 weeks after birth but bovine Ig became undetectable by 14 or 18 weeks. Eight F1-PBL-SCID-bo (23 or 27 weeks of age) were immunized with a single dose of 100 mu g dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH). Individual cells secreting bovine antibody were enumerated using the ELISA-plaque assay. One week after immunization, bovine cells secreting bovine immunoglobulin (IgG) specific for DNP-KLH were identified in the spleens from three of the F1-PBL-SCID-bo at a frequency of one antibody-secreting cell per 9 x 10(3) to 1 x 10(6) spleen cells. Thus, xenogeneic lymphocytes, passed from the mother to her offspring, retain the capacity for a primary immune response to DNP-KLH.

IgA secreting cells located in the lamina propria of the gut are a prominent feature of the mucosal immune system, which serves to protect the body from the continuous threat to infection by intestinal bacteria. In this review we summarize briefly the evidence that these IgA secreting cells have a dual origin and are derived either from conventional B cells or from B-1 cells. Furthermore, we show both at polyclonal and monoclonal levels that the major antigenic target of B-1 cell derived IgA are normal intestinal bacteria. Coating of intestinal bacteria with IgA is thought to result in immune exclusion, as shown for pathogenic bacteria. However, the bacterial microflora of the gut is an extremely stable ecosystem, despite the fact that the majority of intestinal bacteria are coated with IgA. We speculate here that these apparent contradictory functions of the humoral immune system, i.e. removal of bacteria and maintaining the normal gut flora might be exerted by IgA antibodies produced by the two B-cell lineages. The fixed and biased repertoire of B-1 cells might play a role in maintaining the normal intestinal flora. When pathogenic bacteria penetrate into the gut, conventional B cells may be induced in the Peyer's patches to produce high affinity, narrowly tuned IgA antibodies, leading to immune exclusion.

We transferred peritoneal cells from BALB/c mice into C.B17 scid/scid mice. Six to eight months after injection, only cells with the B1 phenotype were retained in the spleens and peritoneal cavities of these mice. The lamina propria of the intestine contained many peritoneal, donor-derived, immunoglobulin A (IgA)-producing cells. The mesenteric lymph nodes of these mice were found to be a major site of proliferation and generation of IgA plasmablasts. We established eight IgA-producing hybridomas from the mesenteric lymph nodes of such mice, and all the hybridomas reacted with different but partially overlapping fecal bacterial populations. Cloning and sequencing of the VH genes of these hybridomas showed that two hybridomas utilized germ line-encoded VH genes while the VH genes of the six hybridomas showed somatic mutations, some of which are indicative of an antigen-driven selection process.

Reactor types for commercial-scale methanol-to-olefins (MTO) processes in the ethene mode, using a small-pore molecular-sieve catalyst, have been evaluated both qualitatively and quantitatively. A kinetic model has been developed via an iterative process of model formulation, parameter estimation, and model validation. The final model consists of 12 reactions involving 6 component lumps plus coke. Important factors are the occurrence of consecutive reactions and the effect of coke on both the activity and selectivity. This kinetic model has been implemented in mathematical models of various reactors for the estimation of product selectivities and main reactor dimensions. These formed the basis for a comparison of different reactor types for a commercial-scale process. A circulating fast fluidized-bed reactor and a turbulent fluidized-bed reactor emerged as the most promising reactor systems for MTO in the ethene mode; ethene/propene ratios of 1--1.5 can be achieved with realistic reactor dimensions.

In this paper we review the existing evidence that peritoneally derived B-1 cells may contribute significantly to the generation of IgA-secreting plasma cells in the murine intestinal lamina propria. The evidence is based upon a variety of experimental approaches performed in our laboratory and others and include (i) transfer studies of (sorted) B-1 cells into B-cell-depleted mice either experimentally (X-irradiation, anti-μ treatment) or genetically (SCID), (ii) analysis of genetically modified or manipulated mice (motheaten mice, CBA/N Xid mice, μ,k transgenic mice), and (iii) transplantation studies of fetal omentum. The data thus support the view that in addition to conventional B cells (B-2 cells) located in the Peyer′s patches (PP), B-1 cells contribute to the pool of IgA containing cells in the gut. Indeed, cotransfer of PP cells and peritoneal cells (PerC), which contain largely B-1 cells, into SCID recipients demonstrates that both PP and PerC contribute in a balanced fashion to the pool of IgA-containing cells in the gut lamina propria over long periods. Most likely IgA-positive (memory) B cells in PP are responsible for the long-term generation of IgA-producing cells derived from the PP inoculum. The potency of B-1 cells to contribute to mucosal IgA responses is also illustrated in adoptive transfer experiments in which PerC B-1 cells (or sorted B-1 cells) are adoptively transferred into untreated, Ig allotype congenic, SCID mice. These studies show that 6 months after injection of a few million PerC, almost all B cells in spleen and the recipient′s peritoneal cavity have the B-1 cell phenotype, while approximately 40 million PerC donor-derived IgA-producing cells can be detected in the gut lamina propria by allotype-specific ELISA spot assays. In conclusion, the data presented here show that, in principle, B-1 cells located in the peritoneal cavity may be an important source of precursors for intestinal IgA plasma cells in the mouse. However, the experiments performed so far do not allow us to draw definitive conclusions yet on the physiological contribution (in terms of numbers) and function (in terms of their specificity repertoire) of both B-1 cells and Peyer′s patch-derived B-2 cells to the pool of IgA-containing cells in the gut lamina propria in normal, unmanipulated animals.

We previously investigated the primary and secondary responses and hyperimmunization to the T cell-dependent antigen 2,4-dinitrophenyl keyhole limpet hemocyanin (DNP-KLH) in antigen-free (AF), germ-free (GF) and conventional (CV) mice. Both the absolute and relative numbers of DNP-specific IgG-secreting cells in the spleen of AF mice were considerably higher compared to GF and CV mice, especially after hyperimmunization. In the present study we measured the total and DNP-specific IgG concentration in the sera of these hyperimmunized mice using a sensitive sandwich enzyme-linked immunosorbent assay. With respect to the total IgG concentration before and after hyperimmunization, the AF mice showed an almost 13-fold increase after boosting with the antigen; the GF mice showed an approximately 8-fold increase. A slight but non-significant increase was observed in the CV mice. The total as well as the DNP-specific IgG levels in the AF-immunized mice were 2-fold and 5-fold higher compared to GF and CV mice, respectively. With the use of Surface Plasmon Resonance instrumentation (BIAcore(TM), Pharmacia, Uppsala, Sweden) we obtained mean binding affinities (K-A) of the polyclonal samples of the three groups of hyperimmunized mice. IgA and IgM samples displayed low affinity for DNP-lysine. The AF mice displayed the highest K-A value among IgG antibodies, followed by GF mice, while CV mice showed a 3-fold lower K-A compared to AF mice. These differences were mainly determined by the dissociation rate constant (k(diss)), since no significant changes were observed in the association rate constant (k(ass)). Furthermore, the sera of the CV mice have a lower percentage of high-affinity antibodies compared to GF and AF mice. These results suggest that besides a higher overall binding affinity seen in AF mice, and to a lesser extent in GF mice, the relative contribution of high-affinity IgG is greater in AF mice compared to CV mice.

Sjogren's Syndrome (SS) is a chronic inflammatory disorder affecting exocrine glands, in particular the lacrimal and salivary glands. The disease can be primary (pSS) or secondary to other systemic autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus and others. The systemic autoimmune character of pSS is also apparent from the occurrence of (non-organ specific) autoantibodies in this disease. Histopathologically, glandular involvement is characterized by focal accumulation of lymphocytes, particularly around epithelial ducts, with, sometimes, germinal center-like structures. The infiltrates largely consist of T-cells, with a preponderance of CD4-positive T-cells. As a result, the pathology in SS was primarily attributed to T cells. However, a break with the fixation on the role of T cells in pSS came when therapeutic B-cell depletion strategies proved remarkably efficacious in this disease, thereby indicating a major role for B-cells in the immunopathogenesis of pSS. In this regard, a closer look at the composition of B-cells and B-cell sub-populations, both in the peripheral blood and in target tissues, is worthwhile. In this review, we discuss current data on B-cells in pSS. B-cell depletion offers a unique possibility to study the recurrence of (pathogenic) B-cells and their characteristics in pSS patients treated with rituximab. Data on B-cell sub-populations in the peripheral blood and B-cell repertoire in the target tissues following rituximab treatment are discussed as well. We also address their state of activation, repertoire, and relation to B-cell activating factor (BAFF).

In Crohn's disease (CD), chronic gut inflammation leads to loss of mucosal barrier integrity. Subsequent leakage of IgG to the gut could produce an increase of IgG coating of intestinal bacteria. We investigated if there is more IgG coating in patients than in volunteers and whether this is dependent on the host IgG response or on the gut bacteria. Fecal and serum samples were obtained from 23 CD patients and 11 healthy volunteers. Both thein vivoIgG-coated fecal bacteria andin vitroIgG coating after serum addition were measured by flow cytometry and related to disease activity. The bacterial composition in feces was determined using fluorescencein situhybridization. The IgG-binding capacities ofEscherichia colistrains isolated from feces of patients and volunteers were assessed. The results showed that thein vivoIgG-coated fraction of fecal bacteria of patients was slightly larger than that of volunteers but significantly larger after incubation with either autologous or heterologous serum. This was dependent on the bacteria and independent of disease activity or the serum used. The presence of moreEnterobacteriaceaeand fewer faecalibacteria in patient feces was confirmed.E. coliisolates from patients bound more IgG than isolates from volunteers (P< 0.05) after the addition of autologous serum. Together, these results indicate that CD patients have more IgG-binding gut bacteria than healthy volunteers. We showed that the level of IgG coating depends on the bacteria and not on the serum used. Furthermore, CD patients have a strong specific immune response to their ownE. colibacteria.

A novel perfectly mixed laboratory reactor for determining kinetics of heterogeneously catalyzed gas-phase reactions has been developed. Perfect mixing is achieved by circulating the gas in the reactor using an axial flow impeller in a well streamlined enclosure. Pellets are fixed in a rectangular opening in the blades of the impeller. They rotate with the impeller, thus realizing high particle velocities in the reactor. Interparticle mass transfer was studied experimentally by vaporization of naphthalene pellets. The mass-transfer coefficient in the novel reactor was found to depend on the velocity of a particle in the reactor. Mass-transfer coefficients in an internal recycle reactor at equal impeller tip speeds are 4-6 times lower than those in the novel reactor, and conditions can be chosen easily where at higher rotational speeds the mass- and heat-transfer rates are 8-10 times higher than in classical recycle reactors. The recycle flow rate in a recycle reactor was found to depend strongly on the resistance to flow caused by the catalyst bed itself. The novel reactor was tested under reacting conditions using the hydrogenation of ethene.

The B cell immune response to 2,4-dinitrophenyl (DNP) keyhole limpet hemocyanin was compared in antigen-free, germ-free and conventional BALB/c mice. The numbers of total and of DNP-specific IgM-, IgG- and IgA-secreting cells in the spleen were determined by enzyme-linked immunosorbent plaque assays after primary, secondary and hyperimmunization. Three days after primary immunization a peak of DNP-specific IgM-secreting cells was seen in conventional mice only. However, this specific response was accompanied by a rise in the total number of IgM-secreting cells. At day 6 after primary immunization the total number and the frequency of DNP-specific IgG-secreting cells were higher in antigen-free mice, compared to germ-free and conventional mice. After secondary immunization in conventional mice only, a considerable bystander IgG response was seen together with the DNP-specific IgG response. At the end of the secondary response 90% of all IgG-secreting cells were DNP specific in antigen-free mice, while the corresponding figure in germ-free and conventional mice was 63% and 14%, respectively. After hyperimmunization, the absolute number of DNP-specific IgG-secreting cells in the spleen was 5-fold and 11-fold higher in antigen-free mice than in germ-free and conventional mice, respectively. Approximately 48% of all IgG-secreting cells were DNP specific in antigen-free mice, while the corresponding figure in germ-free and conventional mice was 17% and 12%, respectively. The results show that the exogenous antigenic load of animals influences the immune response to newly introduced antigens. The higher absolute and relative numbers of antigen-specific IgG-secreting cells after hyperimmunization in antigen-free mice compared to germ-free and conventional mice may provide a better source for antigen-specific B cells that eventually can be used for hybridoma production.

The steady state and dynamic behaviour of an adiabatic packed bed reactor for the selective hydrogenation of mixtures of ethyne and ethene is studied. A heterogeneous model with axial dispersion of heat is solved numerically by means of a fully implicit discretisation scheme. From an analysis of the inlet and outlet boundary conditions, it follows that in order to avoid an influence of the type of boundary condition on the reactor behaviour, sufficiently long inert zones before and after the active bed should be present. Using preliminary kinetic expressions adapted from Mcn'shchikov ct al. (1975), the model calculations show a reasonable agreement with the experiments performed in a laboratory scale reactor and demonstrate the importance influence of small amounts of carbon monoxide both on the steady state as well as on the transient behaviour of the reactor. However, using the rate expressions derived from our own kinetic experiments in a Berty reactor, the behaviour under runaway conditions a...

The steady state and dynamic behaviour of an adiabatic packed bed reactor for the selective hydrogenation of ethyne and ethene mixtures was studied experimentally. Different methods to achieve adiabatic conditions on a laboratory scale were tested. Temperature profiles of both the gas and solid phase as well as local temperature differences between the two phases were measured. For hydrogenation in the absence of carbon monoxide the selectivity was always poor. Also, in that case, the temperature in the reaction zone exhibited oscillatory behaviour. On addition of CO, the oscillations disappeared and the selectivity improved. For a given set of operating conditions there existed a relatively small range of CO contents with good selectivity and satisfactory conversion. This range depends strongly on the inlet temperature. The dynamic response of the reactor to changes in the CO content showed a considerable wrong-way behaviour. This high sensitivity to fluctuations in the CO content, found for our...

The kinetics of the hydrogenation of gas mixtures of ethyne and ethene on a commercial Pd catalyst was studied experimentally using a Berty reactor. The experimental conditions corresponded with typical industrial tail-end conditions, 0.3–1.3% C2H2, 0.4–4% H2, the balance being ethene. The influence of small amounts of carbon monoxide added to the feed gas was also investigated. The pressure was varied between 0.3 and 2.1 MPa and the temperature between 299 and 330 K. The maximum temperature was limited due to mechanical problems of the Berty reactor. Eight different sets of rate expressions, partially adapted from expressions previously proposed in the literature, have been tested. No ‘best” model was chosen, because many models were found to describe the data equally well. The prediction of the rate of ethane formation was less accurate than the prediction of the rate of ethyne hydrogenation. This was not only due to the higher experimental error involved, but also because ethane could be formed by alternative routes. In deriving adequate rate expressions for the rather complex system, a compromise has to be sought between the relative inaccuracy of the simpler expressions and the inability of determining the large number of parameters in more complex expressions.

A review of the kinetics and mechanism for the selective hydrogenation of ethyne and ethene on palladium catalysts is presented. The progress made in the last fifteen years is mainly discussed. It has become clear that the classical view, where the selectivity of the reaction was believed to be due to the thermodynamic factor is an over-simplification. Currently, it is generally assumed that at least two different sites are active during the selective hydrogenation, one of these might possibly involve the support. Ethene hydrogenation also occurs in the presence of high ethyne concentrations, which cannot be explained by the classical theory. Besides the two main hydrogenation reactions and the oligomerisation, there exists a direct route from ethyne to ethane, which, however, is only of minor importance. Possibly due to the rather complex nature of the system, there have been relatively few kinetic studies presenting practical rate expressions.

A review of the kinetics and mechanism for the selective hydrogenation of ethyne and ethene on palladium catalysts is presented. The progress made in the last fifteen years is mainly discussed. It has become clear that the classical view, where the selectivity of the reaction was believed to be due to the thermodynamic factor is an over-simplification. Currently, it is generally assumed that at least two different sites are active during the selective hydrogenation, one of these might possibly involve the support. Ethene hydrogenation also occurs in the presence of high ethyne concentrations, which cannot be explained by the classical theory. Besides the two main hydrogenation reactions and the oligomerisation, there exists a direct route from ethyne to ethane, which, however, is only of minor importance. Possibly due to the rather complex nature of the system, there have been relatively few kinetic studies presenting practical rate expressions.

In this paper we discuss the use of an approximated form of the mass balance equation for a tubular reactor in which a gas phase reaction is carried out. By means of three examples it is shown that if density variations are not taken into account in a correct way, surprisingly high errors can occur. More specifically, if the mass balance is written down in a generally applied approximate form, i.e. using udc/dz instead of d(uc)/dz—u, c and z respectively being the gas velocity, concentration and length coordinate—even for density variations as low as 5%, errors of a magnitude higher than 5% can be introduced. This is particularly true for multiple reaction systems. The inexpediency of approximating d(uc) by udc is stressed: the approximation is in no way a simplification. Therefore, this commonly seen approximation should never be applied.

The gastrointestinal tract is a complex niche and the main port of entry of many pathogens that trigger a wide range of diseases like inflammatory bowel disease (IBD) and colon cancer. Antibodies are effective for treating such diseases, but a System capable of local delivery at the site of the pathology, thus avoiding systemic side effects, is not yet available. Here we report a novel recombinant scFvSIgA1 protein produced by Lactococcus lactis, anchored to the bacterial membrane, which retains its full immuno-recognizing potential. This scFv fragment employed was specific for a colon cancer epilope, epithelial glycoprotein protein-2 (EGP-2). Accordingly L. lactis expressing this chimeric protein was capable of binding cells expressing this epitope. Expression of specific antibodies on bacteria may allow local delivery of anticancer agents produced by Such bacteria ill Conjunction with the antibody and provides a new avenue in the quest for targeted drug delivery.

Publisher Summary Shell has coproduced propylene oxide (PO) and styrene using its proprietary styrene monomer propylene oxide (SMPO) process for three decades. Research, development, and plant trials have been performed on a continuous basis in order to improve its efficiency and cost competitiveness. This chapter discusses the some of the key fundamental and technological learnings gathered over various parts of the process. The heart of the process is formed by the catalytic epoxidation of propylene with ethylbenzene hydroperoxide using a silica-supported titanium catalyst. Fundamental studies have provided models for the active sites, the reaction mechanism, and the cause of catalyst deactivation. Other process elements have been investigated and improved as well. Minor by-products have been tracked across the process to unravel their impact on the various process steps. Computational flow dynamic studies of the air-oxidation step, as well as broad catalytic studies of the dehydration step, have led to significant performance improvements.

The commensal microbiota protects the murine host from enteric pathogens. Nevertheless, specific pathogens are able to colonize the intestinal tract and invade, despite the presence of an intact biota. Possibly, effective pathogens disrupt the indigenous microbiota, either directly through pathogen-commensal interaction, indirectly via the host mucosal immune response to the pathogen, or by a combination of these factors. This study investigates the effect of peroral Salmonella enterica serovar Typhimurium infection on the intestinal microbiota. Since the majority of the intestinal microbiota cannot be cultured by conventional techniques, molecular approaches using 16S rRNA sequences were applied. Several major bacterial groups were assayed using quantitative PCR. Administration of either the 50% lethal dose (LD 50 ) or 10× LD 50 of Salmonella enterica serovar Typhimurium caused changes in the microbiota throughout the intestinal tract over the time course of infection. A 95% decrease in total bacterial number was noted in the cecum and large intestine with 10× LD 50 S. enterica serovar Typhimurium challenge at 7 days postinfection, concurrent with gross evidence of diarrhea. In addition, alterations in microbiota composition preceded the onset of diarrhea, suggesting the involvement of pathogen-commensal interactions and/or host responses unrelated to diarrhea. Microbiota alterations were not permanent and reverted to the microbiota of uninfected mice by 1 month postinfection. Infection with a Salmonella pathogenicity island 1 (SPI1) mutant did not result in microbiota alterations, while SPI2 mutant infections triggered partial changes. Neither mutant was capable of prolonged colonization or induction of mucosal inflammation. These data suggest that several Salmonella virulence factors, particularly those involved in the local mucosal host response, are required for disruption of the intestinal ecosystem.