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Basophils are implicated in the pathogenesis of the late-phase allergic reaction, but the mechanisms by which circulating basophils adhere to vascular endothelium and migrate to lesional sites remain unclear. In order to assess the biological similarity of the basophilic cell line KU-812 to normal human basophils, we have compared the adhesion response of this cell line and normal basophils, following challenge with interleukin-8 (IL-8) and RANTES. We demonstrate here that IL-8 and RANTES are able to stimulate the adherence of the basophilic cell line, KU812, to cytokine-activated human umbilical vein endothelium (HUVEC). The chemokine-induced increase in adhesion was dose-related and was maximal after prior priming with IL-5. The stimulation of adhesion was partially inhibited by co-incubation with anti-CD18 and anti-CD11c antibodies and antibodies to the β1-integrins. In comparison, the chemokine-inducod adhesion of normal human basophils was only inhibited by the β2-integrins. These chemokines were also able to induce the migration of KU-812 in a dose-dependent manner, but only after prior treatment with phorbol myristate acetate (PMA) or IL-5. In all cases tested, IL-8 was more potent and efficacious than RANTES. We conclude from these studies that these members of the chemokine superfamily may play an important role in the recruitment of reactive leukocytes in allergic inflammation, by stimulating their adhesion and subsequent migration from the vasculature into the inflammatory sites. However, it is apparent that KU-812 is not an adequate substitute for normal human basophils in order to investigate chemokine biology. [ABSTRACT FROM AUTHOR]

Actively cycling populations of purified human tonsilar B lymphocytes were examined for their capacity to secrete IgM, IgA, IgE and IgG of all four subclasses in direct response to recombinant cytokines; in some experiments, monoclonal antibody to IgM (anti-μ) was included in order to explore the influence of antigen receptor ligation on immunoglobulin (Ig) production. Enhanced IgM release was seen on culture of the cycling cells with either interleukin-2 (IL-2), IL-4 or interferonalpha (IFN-α). IL-2 and IFN-α also augmented IgA production, whereas IL-4 had no effect on this isotype. IL-4 did, however, encourage the production of the IgG subclasses IgG1, IgG2 and IgG3, while IL-2 augmented IgG1 and IgG3 release and IFN-α increased IgG1 levels, IgG4 production, and that of IgE, failed to be perturbed by any of the cytokines assayed. Neither IL-1α, IL-1β, IL-5 nor IFN-γ significantly altered the profile of Ig isotype release. When confronted with anti-μ, cycling B cells demonstrated a marked suppression in IgM production. Suppression could not be overcome by the addition to culture of the normally IgM-promoting IL-4. Concomitant with the reduction in IgM levels, an increase in IgG release was observed. This was comprised of elevations in IgG1 and IgG3. Although not influencing IgA release directly, anti-μ was found to promote increased IgA production in co-culture with either IL-2 or IFN-α. The findings are discussed in the context of recent findings on Ig isotype control in both human and murine systems. [ABSTRACT FROM AUTHOR]

Highly purified, resting B cells could be induced to grow for up to 10 days by culturing in the presence of a synergistic combination of a turnout-promoting phorbol ester and the calcium ionophore ionomycin. In spite of evident cell death occurring, four to five times as many viable B lymphocytes could be harvested at the end of culture than were initially plated. Soluble factors derived from T cells (interleukin-2, commercial B-cell growth factor) or monocytes (interleukin-1) failed to augment further the growth-promotion observed. Evidence is presented to suggest that an autocrine component might be necessary for maintenance of the cell-cycle and growth initiated by the phorbol ester and calcium ionophore combination. The significance of these findings to B-cell physiology are discussed. [ABSTRACT FROM AUTHOR]

Dendritic cells (DC) are cells of the hematopoletic system specialized in capturing antigens and initiating T cell-mediated immune responses. We show here that human DC generated in vitro by culturing CD34+ cord blood progenitor cells in granulocyte macrophage colony stimulating factor plus tumor necrosis factor-alpha express the Fas antigen (APO-1, CD95) and undergo apoptosis upon triggering of Fas by mAb. However, only a proportion of the cells die in response to Fas ligation, an observation that may be related to the virtual absence of the bcl-2 protein in about half of the cells. Ligation of DC CD40 by culture on CD40L-transfected fibroblastic cells up-regulates the expression of bcl-2 and, concomitantly, renders DC virtually resistant to Fas-induced apoptosis. Parallel experiments with mature, interdigitating dendritic cells (IDC) isolated from tonsils revealed that IDC express Fas but do not enter into apoptosis following Fas ligation, a finding that may be explained by their high levels of bcl-2. Thus, upon encountering antigen-specific T cells, DC become resistant to Fas-induced apoptosis, as a consequence of CD40 ligation and possibly by mechanisms associated to the up-regulation of bcl-2 protein expression. [ABSTRACT FROM AUTHOR]

Experiments were designed in order to compare directly the ability of a new and potent monoclonal anti-μ chain antibody to initiate or maintain stimulation in resting and cycling B lymphocytes, respectively. Resting B cells could be stimulated by soluble anti-μ only in the presence of additional signals; these could be supplied by a high dose of phorbol ester or a combination of interlenkin-4 (IL-4) and the CD40 antibody, G28-5. Immobilization of anti-μ not only increased the magnitude of the resting B-cell response but also diminished the co-factor requirements. The ‘background’ stimulation obtained when using a high concentration of immobilized anti-μ was unexpectedly reduced in the presence of IL-4 alone. The duration, but not the magnitude, of the IL-4 signal required for promoting optimal responses varied with the co-stimulation applied. Importantly, the threshold concentrations of soluble anti-μ needed to trigger the resting B cells were reduced upon the addition of each co-stimulant. With actively cycling B cells, both soluble and immobilized anti-μ were now capable of sustaining stimulation which could be prolonged on the addition of IL-4 and/or G28- 5. In both resting and cycling populations, a strong correlation was noted between the magnitude of stimulation elicited when IL-4 was present and the release of the soluble CD23 molecule. Moreover, IL-4-promoted, but not other, stimulations could be augmented up to 10-fold by the inclusion of the CD23 antibody MHM6. Both the resting and cycling B-cell populations were found to secrete IgM in direct response to IL-4 and 028-5; this factor-driven production of IgM was differentially modulated by soluble and immobilized anti-μ in the two populations. [ABSTRACT FROM AUTHOR]

The ESV-producing marmoset B-cell line (895-8), commonly used as a source of EBV for stimulation and transformation of human B cells, was shown to proliferate in response to supernatants containing human B-cell growth factors (BCGF) derived from PA-activated I cells or the KG-La cell line, and to a commercial low molecular weight BCGF (BCGFlow), but not to recombinant human IL-4 (rhlL-4). In this respect, 895-8 responded in much the same way as human EBV-transformed lymphoblastoid cell lines (LCL). In contrast, B95-8 did not secrete immunoglobulin in response to B-cell differentiation factor (BCDF) containing supernatants from the KG-la cell line, nor to BCGFlow, or IL-6 obtained from the T24 bladder carcinoma cell line, whereas significant responses were obtained with human EBV-transformed LCL. Both B95-8 and control EBV-transformed human LCL secreted BCGF and BCDF detected with the indicator B-cell lines CESS, L4, and HFBI, but only the human LCL secreted BCGF detectable in co-stimulation assays with TPA-activated tonsillar B cells. Unlike EBV-transformed LCL, B95-8 did not express detectable surface CD23, and did not release into the culture medium soluble CD23 (sCD23) recognized by an EIA for the human molecule, Although not releasing detectable sCD23, B95-8 cells did proliferate in response to purified human sCD23, and were found to be 1000 times more sensitive in this assay than EBV-transformed LCL. This may provide a basis for a sensitive bioassay for sCD23. Unlike EBV-transformed LCL, it seems that in vitro proliferation of B95-8 may involve an autocrine loop which does not depend on CD23. [ABSTRACT FROM AUTHOR]

U937 monocytic cells were found to respond by diminished spontaneous migration when confronted with affinity-purified soluble fragments of the low-affinity receptor for IgE (FcER2/CD23). Unlike B lymphoma cells, U937 cells could not be activated to respond with enhanced DNA synthesis through their membrane-bound CD23 antigen by MHM6, a monoclonal antibody within the CD23 cluster. MHM6 did, however, effectively neutralize the U937-directed MIF (migration inhibition factor) activity contained within the soluble CD23 preparations. The findings not only suggest a role for soluble CD23 as a novel cytokine at sites of inflammation but also indicate different functions for the membrane-bound forms expressed on B cells and monocytes. [ABSTRACT FROM AUTHOR]

Introduction: Patients with Human Hyper IgM syndromes (HIGM) developed pulmonary and gastrointestinal infections since infancy and most patients have mutations in the CD40 ligand (CD40L) gene. Most HIGM patients compared to healthy subjects have higher/similar IgM and lower IgG, and IgA serum concentrations but gut antibody concentrations are unknown. CD40L on activated T-cells interacts with CD40 on B-cells, essential for the formation of germinal centres (GCs) inside secondary lymphoid organs (SLOs), where high-affinity antibodies, long-lived antibody-secreting plasma cells, and memory B-cells, are produced. C57BL6-CD40 ligand deficient mice (C57BL6- cd40l -/- ), are a model of HIGM, because serum immunoglobulin concentrations parallel levels observed in HIGM patients and have higher faecal IgA concentrations. In mice, TGFβ and other cytokines induce IgA production., Aims: To compare and evaluate B-cell populations and IgA-producing plasma cells in peritoneal lavage, non-gut-associated SLOs, spleen/inguinal lymph nodes (ILN), and gut-associated SLOs, mesenteric lymph nodes (MLN)/Peyer´s patches (PP) of unimmunised C57BL6- cd40l -/- and C57BL6-wild-type (WT) mice., Material and Methods: Peritoneal lavages, spleens, ILN, MLN, and PP from 8-10 weeks old C57BL6- cd40l -/- and WT mice, were obtained. Organ cryosections were analysed by immunofluorescence and B-cell populations and IgA-positive plasma cell suspensions by flow cytometry., Results: In unimmunised WT mice, GCs were only observed in the gut-associated SLOs, but GCs were absent in all C57BL6- cd40l -/- SLOs. PP and MLN of C57BL6- cd40l -/- mice exhibited a significantly higher number of IgA-producing cells than WT mice. In the spleen and ILN of C57BL6- cd40l - /- mice IgA-producing cells significantly decreased, while IgM-positive plasma cells increased. C57BL6- cd40l -/- B-1 cells were more abundant in all analysed SLOs, whereas in WT mice most B-1 cells were contained within the peritoneal cavity. C57BL6- cd40l -/- B-cells in MLN expressed a higher TGFβ receptor-1 than WT mice. Mouse strains small intestine microvilli (MV), have a similar frequency of IgA-positive cells., Discussion: Together our results confirm the role of PP and MLN as gut inductive sites, whose characteristic features are to initiate an IgA preferential immune response production in these anatomical sites even in the absence of GCs. IgA antibodies play a pivotal role in neutralising, eliminating, and regulating potential pathogens and microorganisms in the gut., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Hernandez-Cazares, Maqueda-Alfaro, Lopez-Saucedo, Martinez-Barnetche, Yam-Puc, Estrada-Parra, Flores-Romo and Estrada-Garcia.)

Multiple mechanisms restrain inflammation in neonates, most likely to prevent tissue damage caused by overly robust immune responses against newly encountered pathogens. Here, we identify a population of pulmonary dendritic cells (DCs) that express intermediate levels of CD103 (CD103 int ) and appear in the lungs and lung-draining lymph nodes of mice between birth and 2 weeks of age. CD103 int DCs express XCR1 and CD205 and require expression of the transcription factor BATF3 for development, suggesting that they belong to the cDC1 lineage. In addition, CD103 int DCs express CCR7 constitutively and spontaneously migrate to the lung-draining lymph node, where they promote stromal cell maturation and lymph node expansion. CD103 int DCs mature independently of microbial exposure and TRIF- or MyD88-dependent signaling and are transcriptionally related to efferocytic and tolerogenic DCs as well as mature, regulatory DCs. Correlating with this, CD103 int DCs show limited ability to stimulate proliferation and IFN-γ production by CD8 + T cells. Moreover, CD103 int DCs acquire apoptotic cells efficiently, in a process that is dependent on the expression of the TAM receptor, Mertk, which drives their homeostatic maturation. The appearance of CD103 int DCs coincides with a temporal wave of apoptosis in developing lungs and explains, in part, dampened pulmonary immunity in neonatal mice. Together, these data suggest a mechanism by which DCs sense apoptotic cells at sites of noninflammatory tissue remodeling, such as tumors or the developing lungs, and limit local T cell responses.

Dendritic cells form the link between the innate and adaptative immune response, particularly on mucosal and epidermal surfaces. The Langerhans, an epidermal dendritic cell subpopulation, play a key role in the skin immune response across several species. Scarse immune cell subpopulations, including Langerhans-like cells, have been identified in endangered green turtles thereby complicating the understanding of the pathogenesis of diseases such as fibropapillomatosis, which induces skin tumours in this species worldwide. In biopsies from green turtle skin, we demonstrated that the polyclonal anti-human Langerin antibodies strongly stained a Langerin+ cell population in epidermal sheets, the suprabasal layer of the epidermis in cryosections and in cells from cytospin preparation of migration assays. The morphology of these cells was round to amoeboid in normal skin; however, in skin with ulcerative dermatitis, Langerin+ cells aggregated around ulcers and adopted a more pleomorphic morphology. To our knowledge, this is the first identification of Langerin+ cells with a molecular marker in a reptile species., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Purpose: Neonatal sepsis is an important public health concern worldwide due to its immediate lethality and long-term morbidity rates, Clinical evaluation and laboratory analyses are indispensable for diagnosis of neonatal sepsis. However, assessing multiple biomarkers in neonates is difficult due to limited blood availability. The aim is to investigate if the neonatal sepsis in preterm could be identified by multiparameter analysis with flow cytometry., Materials and Methods: The expression of activation-related molecules was evaluated by flow cytometry in newborn with or without risk factors for sepsis., Results: Our analysis revealed that several markers could be useful for sepsis diagnosis, such as CD45RA, CD45RO, or CD71 on T cells; HLA-DR on NKT or classic monocytes, and TREM-1 on non-classic monocytes or neutrophils. However, ROC analysis shows that the expression of CD45RO on T lymphocytes is the only useful biomarker for diagnosis of neonatal late-onset sepsis. Also, decision tree analyses showed that CD45RO plus CD27 could help differentiate the preterm septic neonates from those with risk factors., Conclusions: Our study shows a complementary and practical strategy for biomarker assessment in neonatal sepsis.

Dengue is a worldwide expanding threat caused by dengue virus (DENV) infection. To date, no specific treatment or effective vaccine is available. Antibodies produced by plasma cells (PCs) might be involved concomitantly in protection and severe dengue immunopathology. Although a massive appearance of PCs has been reported during acute DENV infection in humans, this response has been poorly characterized. Here, we show the dynamic of PC generation in immune-competent mice cutaneously inoculated with DENV compared with two control experimental groups: mice inoculated with inactivated DENV or with PBS. We found that PC numbers increased significantly in the skin-draining lymph node (DLN), peaking at day 10 and abruptly decreasing by day 14 after DENV inoculation. Class-switched IgG + PCs appeared from day 7 and dominated the response, while in contrast, the frequency of IgM + PCs decreased from day 7 onwards. Even though the kinetic of the response was similar between DENV- and iDENV-inoculated mice, the intensity of the response was significantly different. Interestingly, we demonstrated a similar PC response to virus antigens (E and prM) by ELISPOT. In situ characterization showed that PCs were distributed in the medullary cords and in close proximity to germinal centers (GCs), suggesting both an extrafollicular and a GC origin. Proliferating PCs (Ki-67 + ) were found as early as 3-day postinoculation, and in-depth analysis showed that these PCs were in active phases of cell cycle during the kinetic. Finally, we found a progressive appearance of high-affinity neutralizing DENV-specific IgG further supporting GC involvement. Of note, these antibodies seem to be highly cross-reactive, as a large proportion recognizes Zika virus (ZIKV). The strong PC response to skin-inoculated DENV in this work resembles the findings already described in humans. We consider that this study contributes to the understanding of the in vivo biology of the humoral immune response to DENV in an immunocompetent murine model., Competing Interests: The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2021 Raúl A. Maqueda-Alfaro et al.)

Gaining knowledge of the neoplastic side of the three main cells-B cells, Follicular Helper T (Tfh) cells, and follicular dendritic cells (FDCs) -involved in the germinal center (GC) reaction can shed light toward further understanding the microuniverse that is the GC, opening the possibility of better treatments. This paper gives a review of the more complex underlying mechanisms involved in the malignant transformations that take place in the GC. Whilst our understanding of the biology of the GC-related B cell lymphomas has increased-this is not reviewed in detail here-the dark side involving neoplasms of Tfh cells and FDCs are poorly studied, in great part, due to their low incidence. The aggressive behavior of Tfh lymphomas and the metastatic potential of FDCs sarcomas make them clinically relevant, merit further attention and are the main focus of this review. Tfh cells and FDCs malignancies can often be misdiagnosed. The better understanding of these entities linked to their molecular and genetic characterization will lead to prediction of high-risk patients, better diagnosis, prognosis, and treatments based on molecular profiles., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Munguía-Fuentes, Maqueda-Alfaro, Chacón-Salinas, Flores-Romo and Yam-Puc.)

Dengue virus infection (DENV-2) is transmitted by infected mosquitoes via the skin, where many dermal and epidermal cells are potentially susceptible to infection. Most of the cells in an area of infection will establish an antiviral microenvironment to control viral replication. Although cumulative studies report permissive DENV-2 infection in dendritic cells, keratinocytes, and fibroblasts, among other cells also infected, little information is available regarding cell-to-cell crosstalk and the effect of this on the outcome of the infection. Therefore, our study focused on understanding the contribution of fibroblast and dendritic cell crosstalk to the control or promotion of dengue. Our results suggest that dendritic cells promote an antiviral state over fibroblasts by enhancing the production of type I interferon, but not proinflammatory cytokines. Infected and non-infected fibroblasts promoted partial dendritic cell maturation, and the fibroblast-matured cells were less permissive to infection and showed enhanced type I interferon production. We also observed that the soluble mediators produced by non-infected or Poly (I:C) transfected fibroblasts induced allogenic T cell proliferation, but mediators produced by DENV-2 infected fibroblasts inhibited this phenomenon. Additionally, the effects of fibroblast soluble mediators on CD14 + monocytes were analyzed to assess whether they affected the differentiation of monocyte derived dendritic cells (moDC). Our data showed that mediators produced by infected fibroblasts induced variable levels of monocyte differentiation into dendritic cells, even in the presence of recombinant GM-CSF and IL-4. Cells with dendritic cell-like morphology appeared in the culture; however, flow cytometry analysis showed that the mediators did not fully downregulate CD14 nor did they upregulate CD1a. Our data revealed that fibroblast-dendritic cell crosstalk promoted an antiviral response mediated manly by type I interferons over fibroblasts. Furthermore, the maturation of dendritic cells and T cell proliferation were promoted, which was inhibited by DENV-2-induced mediators. Together, our results suggest that activation of the adaptive immune response is influenced by the crosstalk of skin resident cells and the intensity of innate immune responses established in the microenvironment of the infected skin., (Copyright © 2020 Montes-Gómez, García-Cordero, Marcial-Juárez, Shrivastava, Visoso-Carvajal, Juárez-Delgado, Flores-Romo, Sanchez-Torres, Santos-Argumedo, Bustos-Arriaga and Cedillo-Barrón.)

Similar to what has been described in other Gram-negative bacteria, Brucella melitensis releases outer membrane vesicles (OMVs). OMVs from B. melitensis 16M and the rough-mutant B. melitensis VTRM1 were able to induce a protective immune response against virulent B. melitensis in mice models. The presence of some proteins which had previously been reported to induce protection against Brucella were found in the proteome of OMVs from B. melitensis 16M. However, the proteome of OMVs from B. melitensis VTRM1 had not previously been determined. In order to be better understand the role of OMVs in host-cell interactions, the aim of this work was to compare the proteomes of OMVs from B. melitensis 16M and the derived rough-mutant B. melitensis VTRM1, as well as to characterize the immune response induced by vesicles on host cells. Additionally, the effect of SDS and proteinase K on the stability of OMVs was analyzed. OMVs from B. melitensis 16M (smooth strain) and the B. melitensis VTRM1 rough mutant (lacking the O -polysaccharide side chain) were analyzed through liquid chromatography-mass spectrometry (LC-MS/MS). OMVs were treated with proteinase K, sodium deoxycholate, and SDS, and then their protein profile was determined using SDS-PAGE. Furthermore, PBMCs were treated with OMVs in order to measure their effect on cytoskeleton, surface molecules, apoptosis, DNA damage, proliferation, and cytokine-induction. A total of 131 proteins were identified in OMVs from B. melitensis 16M, and 43 in OMVs from B. melitensis VTRM1. Proteome comparison showed that 22 orthologous proteins were common in vesicles from both strains, and their core proteome contained Omp31, Omp25, GroL, and Omp16. After a subsequent detergent and enzyme treatment, OMVs from B. melitensis VTRM1 exhibited higher sensitive compared to OMVs from the B. melitensis 16M strain. Neither OMVs induced IL-17, proliferation, apoptosis or DNA damage. Nonetheless, OMVs from the smooth and rough strains induced overproduction of TNFα and IL-6, as well as actin and tubulin rearrangements in the cytoskeleton. Moreover, OMVs from both strains inhibited PD-L1 expression in T-cells. These data revealed significant differences in OMVs derived from the rough and smooth Brucella strains, among which, the presence or absence of complete LPS appeared to be crucial to protect proteins contained within vesicles and to drive the immune response., (Copyright © 2020 Avila-Calderón, Medina-Chávez, Flores-Romo, Hernández-Hernández, Donis-Maturano, López-Merino, Arellano-Reynoso, Aguilera-Arreola, Ruiz, Gomez-Lunar, Witonsky and Contreras-Rodríguez.)

Dengue is a global health problem without current specific treatment nor safe vaccines available. While severe dengue is related to pre-existing non-neutralizing dengue virus (DENV) antibodies, the role of T cells in protection or pathology is unclear. Using cutaneous DENV infection in immunocompetent mice we previously showed the generation of PNA+ germinal centers (GCs), now we assessed the activation and proliferation of B and T cells in draining lymph nodes (DLNs). We found a drastic remodelling of DLN compartments from 7 to 14 days post-infection (dpi) with greatly enlarged B cell follicles, occupying almost half of the DLN area compared to ~24% in naïve conditions. Enormous clusters of proliferating (Ki-67+) cells inside B follicles were found 14 dpi, representing ~33% of B cells in DLNs but only ~2% in non-infected mice. Inside GCs, we noticed an important recruitment of tingle body macrophages removing apoptotic cells. In contrast, the percentage of paracortex area and total T cells decreased by 14-16 dpi, compared to controls. Scattered randomly distributed Ki-67+ T cells were found, similar to non-infected mice. CD69 expression by CD4+ and CD8+ T cells was minor, while it was remarkable in B cells, representing 1764.7% of change from basal levels 3 dpi. The apparent lack of T cell responses cannot be attributed to apoptosis since no significant differences were observed compared to non-infected mice. This study shows massive B cell activation and proliferation in DLNs upon DENV infection. In contrast, we found very poor, almost absent CD4+ and CD8+ T cell responses.

Antigen capturing at the periphery is one of the earliest, crucial functions of antigen-presenting cells (APCs) to initiate immune responses. Langerhans cells (LCs), the epidermal APCs migrate to draining lymph nodes (DLNs) upon acquiring antigens. An arsenal of endocytic molecules is available to this end, including lectins and pathogen recognition receptors (PRRs). However, cutaneous LCs are poorly defined in the early neonatal period. We assessed endocytic molecules expression in situ : Mannose (CD206)-, Scavenger (SRA/CD204)-, Complement (CD2l, CDllb)-, and Fc-Receptors (CD16/32, CD23) as well as CD1d, CD14, CD205, Langerin (CD207), MHCII, and TLR4 in unperturbed epidermal LCs from both adult and early neonatal mice. As most of these markers were negative at birth (day 0), LC presence was revealed with the conspicuous, epidermal LC-restricted ADPase (and confirmed with CD45) staining detecting that they were as numerous as adult ones. Unexpectedly, most LCs at day 0 expressed CD14 and CD204 while very few were MHCII+ and TLR4+. In contrast, adult LCs lacked all these markers except Langerin, CD205, CD11b, MHCII and TLR4. Intriguingly, the CD204+ and CD14+ LCs predominant at day 0, apparently disappeared by day 4. Upon cutaneous FITC application, LCs were reduced in the skin and a CD204+MHCII+FITC+ population with high levels of CD86 subsequently appeared in DLNs, with a concomitant increased percentage of CD3+CD69+ T cells, strongly suggesting that neonatal LCs were able both to ferry the cutaneous antigen into DLNs and to activate neonatal T cells in vivo . Cell cycle analysis indicated that neonatal T cells in DLNs responded with proliferation. Our study reveals that epidermal LCs are present at birth, but their repertoire of endocytic molecules and PRRs differs to that of adult ones. We believe this to be the first description of CDl4, CD204 and TLR4 in neonatal epidermal LCs in situ . Newborns' LCs express molecules to detect antigens during early postnatal periods, are able to take up local antigens and to ferry them into DLNs conveying the information to responsive neonatal T cells., (Copyright © 2020 Becerril-García, Yam-Puc, Maqueda-Alfaro, Beristain-Covarrubias, Heras-Chavarría, Gallegos-Hernández, Calderón-Amador, Munguía-Fuentes, Donis-Maturano, Flores-Langarica and Flores-Romo.)

As dendritic cells (DCs) are among the first cells to encounter antigens, these cells trigger both innate and T cell responses, and are the most potent antigen-presenting cells. Brucella spp., which is an intracellular facultative and stealthy pathogen, is able to evade the bactericidal activities of professional phagocytes. Several studies have demonstrated that Brucella can survive and replicate intracellularly, thereby provoking impaired maturation of DCs. Therefore, the interaction between DCs and Brucella becomes an interesting model to study the immune response. In this review, we first will describe the most common techniques for DCs differentiation in vitro as well as general features of brucellosis. Then, the interaction of DCs and Brucella, including pathogen recognition, molecular mechanisms of bacterial pathogenesis, and intracellular trafficking of Brucella to subvert innate response, will be reviewed. Finally, we will debate diversity in immunological DC response and the controversial role of DC activation against Brucella infection.

Membrane blebs are released from Gram-negative bacteria, however, little is known about Brucella blebs. This work pursued two objectives, the first was to determine and identify the proteins in the membrane blebs by proteomics and in silico analysis. The second aim was to evaluate the use of membrane blebs of Brucella abortus 2308 and B. abortus RB51 as an acellular vaccine in vivo and in vitro . To achieve these aims, membrane blebs from B. abortus 2308 and RB51 were obtained and then analyzed by liquid chromatography coupled to mass spectrometry. Brucella membrane blebs were used as a "vaccine" to induce an immune response in BALB/c mice, using the strain B. abortus RB51 as a positive vaccine control. After subsequent challenge with B. abortus 2308, CFUs in spleens were determined; and immunoglobulins IgG1 and IgG2a were measured in murine serum by ELISA. Also, activation and costimulatory molecules induced by membrane blebs were analyzed in splenocytes by flow cytometry. Two hundred and twenty eight proteins were identified in 2308 membrane blebs and 171 in RB51 blebs, some of them are well-known Brucella immunogens such as SodC, Omp2b, Omp2a, Omp10, Omp16, and Omp19. Mice immunized with membrane blebs from rough or smooth B. abortus induced similar protective immune responses as well as the vaccine B. abortus RB51 after the challenge with virulent strain B. abortus 2308 ( P < 0.05). The levels of IgG2a in mice vaccinated with 2308 membrane blebs were higher than those vaccinated with RB51 membrane blebs or B. abortus RB51 post-boosting. Moreover, mice immunized with 2308 blebs increased the percentage of activated B cells (CD19 + CD69 + ) in vitro. Therefore, membrane blebs are potential candidates for the development of an acellular vaccine against brucellosis, especially those derived from the rough strains so that serological diagnostic is not affected., (Copyright © 2019 Araiza-Villanueva, Avila-Calderón, Flores-Romo, Calderón-Amador, Sriranganathan, Qublan, Witonsky, Aguilera-Arreola, Ruiz-Palma, Ruiz, Suárez-Güemes, Gómez-Lunar and Contreras-Rodríguez.)