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Ginsenoside Rg3 is a natural active ingredient that is extracted from Korean red ginseng root. It elevates the therapeutic effect of radiotherapy and chemotherapy, but previous studies found that the application of Rg3 is heavily limited by its low bioavailability and poor absorption via oral administration. To overcome these problems, Rg3-loaded PEG-PLGA-NPs (Rg3-NPs) were prepared by the modified spontaneous emulsification solvent diffusion (SESD) method, and the physicochemical characteristics of Rg3-NPs were investigated. We treated primary glioblastoma with 50 mM Rg3-NPs for 48h. We then used gene expression arrays (Illumina) for genome-wide expression analysis and validated the results for genes of interest by means of real-time PCR. Functional annotations were then performed using the DAVID and KEGG online tools. The results showed that the Rg3-NPs are slick and uniform, the average diameter of the nanoparticles is 75-90 nm, and their entrapment efficiency is 89.7+1.7%. MTT showed that the growth of cells can be significantly inhibited by Rg3-NPs in a dose-dependent manner. FCM testing showed Rg3-NPs can be released from the conjugate nanoparticle and react with the genes in the cell nuclei, causing changes in the gene molecules. We also found that cancer cells treated with Rg3-NPs undergo cell-cycle arrest at different checkpoints. This arrest was associated with a decrease in the mRNA levels of core regulatory genes BUB1, CDC20, TTK, and CENPE, as determined by microarray analysis and verified by real-time PCR. Furthermore, Rg3-NPs induced the expression of the apoptotic and antimigratory protein p53 in cell lines. The results of the present study, together with the results of earlier studies, show that Rg3-NPs target genes involved in theprogressionoftheM-phaseofthecellcycle.Itisassociatedwithseveralimportant pathways, which include apoptosis (p53). Rg3-NPs may be a potent cell-cycle regulation drug targeting the M-phase in glioblastoma cell lines.

The 16th Annual Scientific Meeting of the Society for Neuro-Oncology in Conjunction with the AANS/CNS Section on Tumors, Orange County, California, USA, 17-20 November 2011. In Neuro-Oncology, 2011, v. 13 n. Suppl. 3, p. iii111, abstract no. ET-18

We used three anti-human anti-CD3 mAb each recognizing different surface CD3 epitopes to differentially perturb the CD3/TCR complex on the surface of Jurkat T cells. In the presence of phorbol ester, these anti-CD3 mAb triggered differential IL-2 production in Jurkat T cells, which could not be explained by differences in kinetics of IL-2 production, by differences in IL-2 adsorption caused by differential surface expression of p55 or p75 IL-2R, by effects on IL-2 secretion rather than actual synthesis, or by differential toxicities of the anti-CD3 mAb to Jurkat cells. In addition, this differential anti-CD3-induced IL-2 production could not be explained by differences in mAb isotype or in avidities of the anti-CD3 mAb for the Jurkat cells. Moreover, anti-CD3 mAb covalently immobilized onto beads also differentially induced IL-2 production in Jurkat cells, suggesting that the differential IL-2 response is not based on differential rates of anti-CD3-induced modulation of Jurkat cell surface CD3. Although differences among the anti-CD3 mAb in the initial rates of binding to Jurkat cell were observed, this was also believed unlikely to explain the differential IL-2 response. Regardless of the anti-CD3 mAb used, anti-CD3-induced total inositol phosphate (IP) production did not necessarily correlate with anti-CD3-induced IL-2 production. Nevertheless, despite the differences among the anti-CD3 mAb in inducing IL-2 production, the calcium responses were grossly similar. Taken together, these observations indicate that CD3/TCR-mediated IL-2 production in Jurkat cells can be dissociated from total IP generation, and the basis of differential CD3/TCR-mediated IL-2 production in these cells does not appear to be at the level of the initial activation-induced calcium response. These studies suggest that the nature of the CD3/TCR ligand (its physical form and/or the specific epitope it perturbs) can either directly influence intracellular events distal to the generation of IP and increase in intracellular free calcium leading to differential IL-2 production or can trigger IP-independent pathways that affect IL-2 production.

We have previously demonstrated that endothelin-1 (Et-1) induces human central nervous system-derived endothelial cells (CNS-EC) to produce and secrete the chemokine interleukin 8 (IL-8). In the present study, we use specific inhibitors and activators to elucidate the signal transduction pathways involved in this process. Et-1-induced IL-8 production was blocked by ET(A) receptor antagonist BQ610, but not by ET(B) receptor antagonist BQ788, demonstrating that CNS-EC activation is initiated by Et-1 binding to the ET(A) receptor. IL-8 mRNA expression is blocked by the protein kinase C inhibitor bisindolylmaleimide or protein tyrosine kinase inhibitors, genestein and geldanamycin, establishing the involvement of the protein kinase C and protein tyrosine kinase pathways in the activation process. The transcription factor, NF-kappaB, is involved in Et-1 activation as determined by specific inhibitors of translocation and direct analysis of DNA-binding proteins. Neither inhibition nor activation of cAMP-dependent protein kinase affected IL-8 production in the absence or presence of Et-1. Similarly, no effect was observed upon inhibition of protein phosphatases by okadaic acid. Thus, the signal transduction process induced by Et-1 in CNS-EC, leading to increased mRNA IL-8 expression, is initiated by Et-1 binding to ET(A) receptor followed by subsequent activation of protein kinase C, protein tyrosine kinase, and NF-kappaB. Because increased expression of Et-1 is associated with hypertension and stroke and IL-8 is likely to be involved in the accumulation of neutrophils causing tissue damage in ischemic/reperfusion injury, identification of the mechanism involved in the Et-1-induced increase in IL-8 production may have significant therapeutic value.

Increased levels of endothelin-1 (Et-1), a potent vasoconstrictor, have been correlated with hypertension and neuronal damage in ischemic/reperfusion injury. The presence of polymorphonuclear cells (PMNs) in the brain has been shown to be directly responsible for this observed pathology. To address the question of whether Et-1 plays a role in this process, human brain-derived endothelial cells (CNS-ECs) were cultured with Et-1. The results demonstrate that Et-1 induces production of the neutrophil chemoattractant interleukin-8 (IL-8) twofold to threefold after 72 hours; mRNA was maximal after 1 hour of stimulation. Conditioned culture medium derived from Et-1-stimulated CNS-ECs induced a chemotactic response in the PMN migration assay. The inflammatory cytokines tumor necrosis factor-alpha (TNF) and IL-1beta functioned additively with Et-1 in increasing IL-8 production. In contrast, transforming growth factor-beta (TGF-beta), but not IL-10, completely abolished the effect of Et-1 on IL-8 production. However, Et-1 did not modulate intercellular adhesion molecule-1 (ICAM-1) expression. These data demonstrate that Et-1 may be a risk factor in ischemic/reperfusion injury by inducing increased levels of the neutrophil chemoattractant IL-8.

Manipulation of signal transduction pathways has been increasingly used to modulate tumor growth. We have investigated the effects of up-regulation of the cAMP/protein kinase A (PKA) pathway in cell lines and primary cultures of malignant gliomas. The malignant glioma cell line A-172 was treated with agonistic cAMP analogs dibutyryl cyclic AMP (dcAMP) and 8-bromo-cyclic AMP (8-Br-cAMP), an adenylate cyclase activator (forskolin), and a phosphodiesterase inhibitor (3-isobutyl-1-methyl-xanthene [IBMX]). Proliferation was determined by 3H-thymidine assay. Differentiation was measured by morphologic changes, glial fibrillary acidic protein (GFAP) content, and invasion potential. Apoptosis was measured quantitatively by the TUNEL method, which labels DNA fragments using terminal transferase. Agonistic cAMP analogs, forskolin, and IBMX were found to decrease proliferation in A-172 cells after 24 hours. Treatment with 8-Br-cAMP for 24 hours caused an increase in GFAP and decrease in invasion. Apoptosis was induced after 48 hours in the presence of synergistic cAMP analogs for the Type II PKA isozyme, but not Type I PKA isozyme. Activation of PKA by increasing cAMP levels (forskolin, IBMX) or directly by cAMP analogs correlated with decreased proliferation, increased differentiation, and induction of apoptosis in A-172 cells. Modulation of the cAMP/PKA pathway may thus represent a possible target site for treating malignant gliomas.

Proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) play an important role in the blood-brain barrier breakdown present in several neurological diseases including multiple sclerosis and AIDS. However, the specific effects of these cytokines on central nervous system-derived endothelial cells (CNS-EC) is not fully understood. In this study the effects of TNF-alpha and IL-6 were tested on different permeability mechanisms of CNS-EC.Central nervous system endothelial cells were isolated from human brain and retina and cultured in vitro in a transwell system. Fluid-phase endocytosis and transcytosis, absorptive-mediated endocytosis, and ammonia diffusion were measured with specific methods. Endothelial cells were studied with electron microscopy for the ultrastructural effects of cytokine stimulation.Fluid-phase endocytosis and transcytosis were significantly increased by TNF-alpha and IL-6. This effect was dose dependent and reversible. The ammonia diffusion rate was also significantly increased by TNF-alpha. Absorptive-mediated endocytosis was not enhanced by TNF-alpha. Ultrastructural analysis of cytokine-treated CNS-EC confirmed the alterations in permeability showing an increase in endocytotic activity and a decrease in tight junctions.The proinflammatory cytokines IL-6 and TNF-alpha induce specific changes in the morphology and permeability of CNS-EC. These alterations can be important in many diseases characterized by increased cytokine production.

To determine second messenger signaling pathways associated with tumor necrosis factor-alpha (TNF)-mediated induction of intercellular adhesion molecule (ICAM)-1 expression on human retinal pigment epithelial (HRPE) cells, a cell type known to express only the 55-kDa TNF receptor (TNFR p55).SV 40-immortalized HRPE (SVRPE) cells were exposed to TNF with and without pretreatment with the protein kinase C (PKC) inhibitor calphostin C or the protein kinase A (PKA) inhibitor H8. SV40-immortalized HRPE cells also were treated with the PKC activator phorbol 12-myristate 13-acetate (PMA) or with the PKA activators forskolin plus 3-isobutyl-1-methyl-xanthine or dibutyryl cyclic adenosine monophosphate (cAMP) alone. Membrane fractions from untreated and treated SVRPE cells were assayed for PKC activity, and whole cell lysates were assayed for cAMP accumulation and PKA activity. Flow cytometry was performed on SVRPE cells using a monoclonal antibody specific to ICAM-1.Activation of TNFR p55 on SVRPE cells with TNF resulted in a rapid increase of PKC activity at 1 minute, with a subsequent downregulation to baseline. There was no increase in intracellular cAMP accumulation or PKA activity within the first 10 minutes; however, both increased within 30 minutes and returned to baseline within 1 hour. SV40-immortalized HRPE cells treated with TNF for 1 hour showed maximal induction of ICAM-1 expression at 18 hours. ICAM-1 induction by TNF treatment was inhibited by calphostin C pretreatment and not by H8 pretreatment. Protein kinase C activation with PMA for 3 hours was sufficient to induce ICAM-1 on SVRPE cells at 18 hours, whereas treatment with the PKA activators forskolin or dibutyryl cAMP did not induce ICAM-1 expression.Tumor necrosis factor sequentially activates the PKC and PKA pathways in SVRPE cells by way of the TNFR p55. The PKC pathway in necessary for TNF-mediated ICAM-1 upregulation, and specific activation of the PKC pathway with PMA is sufficient to induce ICAM-1 on these cells. SV40-immortalized HRPE cells may serve as a model in which to study further the functional signaling pathways associated with TNFR p55.

Tumor necrosis factor (TNF)-alpha has been shown to be increased in brain tissue of AIDS patients and may function as a mediator of cerebral damage. We initiated a study to determine the cellular localization and degree of protein and mRNA expression of the two specific TNF-alpha receptors (TNF-Rs), p55 and p75, in brain tissues from AIDS patients. Cerebral white matter obtained at autopsy from 13 AIDS patients, 10 unhealthy controls, and 4 healthy controls was evaluated. Double-label immunohistochemistry revealed prominent up-regulation of p55 and p75 TNF-Rs on activated macrophages and microglial cells in all AIDS patients; no increased staining was found on astrocytes. Staining was most prominent in patients with opportunistic infection of the brain and in microglial nodules of patients with HIV encephalitis. Brain tissues also showed increased expression of interleukin (IL)-1 beta, IL-6, and TNF-alpha, cytokines known to up-regulate the TNF-Rs. Increased staining for TNF-Rs was also found in patients with multiple sclerosis, chronic cerebral edema, and radiation necrosis but not in an asymptomatic HIV-positive patient without AIDS. Reverse transcriptase polymerase chain reaction performed on adjacent sections from five AIDS patients revealed up-regulation from normal for p55 in all patients and for p75 in three patients. The up-regulation of both TNF-Rs in AIDS suggests that macrophages and microglial cells may be important in amplifying the TNF-alpha response.

To correlate specific local immune responses with protection from corneal scarring, we examined immune cell infiltrates in the cornea after ocular challenge of vaccinated mice with herpes simplex virus type 1 (HSV-1). This is the first report to examine corneal infiltrates following ocular challenge of a vaccinated mouse rather than following infection of a naive mouse. Mice were vaccinated systemically with vaccines that following ocular challenge with HSV-1 resulted in (i) complete protection against corneal disease (KOS, an avirulent strain of HSV-1); (ii) partial protection, resulting in moderate corneal disease (baculovirus-expressed HSV-1 glycoprotein E [gE]); and (iii) no protection, resulting in severe corneal disease (mock vaccine). Infiltration into the cornea of CD4+ T cells, CD8+ T cells, macrophages, and cells containing various lymphokines was monitored on days 0, 1, 3, 7, and 10 postchallenge by immunocytochemistry of corneal sections. Prior to ocular challenge, no eye disease or corneal infiltrates were detected in any mice. KOS-vaccinated mice developed high HSV-1 neutralizing antibody titers (> 1:640) in serum. After ocular challenge, they were completely protected against death, developed no corneal disease, and had no detectable virus in their tear films at any time examined. In response to the ocular challenge, these mice developed high local levels of infiltrating CD4+ T cells and cells containing interleukin-2 (IL-2), IL-4, IL-6, or tumor necrosis factor alpha (TNF-alpha). In contrast, only low levels of infiltrating CD8+ T cells were found, and gamma interferon (IFN-gamma)-containing cells were not present until day 10. gE-vaccinated mice developed neutralizing antibody titers in serum almost as high as those of the KOS-vaccinated mice (> 1:320). After ocular challenge, they were also completely protected against death. However, the gE-vaccinated mice developed low levels of corneal disease and virus was detected in one-third of their eyes. Compared with KOS-vaccinated mice, the gE-vaccinated mice had a similar pattern of IFN-gamma, but a delay in the appearance of CD4+ T cells, CD8+ T cells, and IL-4-, IL-6-, and TNF-alpha-containing cells. In sharp contrast to those of the KOS-vaccinated mice, no cells containing IL-2 were detected in the eyes of gE-vaccinated mice at any time. Mock-vaccinated mice developed no detectable neutralizing antibody titer and were not protected from lethal HSV-1 challenge.(ABSTRACT TRUNCATED AT 400 WORDS)

tat protein, a human immunodeficiency virus (HIV) gene product that functions as a transactivator for HIV replication, is known to be secreted extracellularly by infected cells. To determine the potential role of tat in the dissemination of HIV into extravascular tissue, this protein was examined for its ability to activate human endothelial cells. The results show that tat does indeed stimulate endothelial cells. This is evidenced by their expression of the endothelial-leukocyte adhesion molecules, E-selectin, critical for the initial binding of leukocytes to the blood vessel wall, and their increased synthesis of interleukin-6 (IL-6), a cytokine known to enhance endothelial cell permeability. Furthermore, tat acts synergistically with low concentrations of tumor necrosis factor-alpha to enhance IL-6 secretion. These data suggest that extracellular tat protein secreted or released into the microenvironment may contribute significantly to the determination of specific sites of leukocyte binding to blood vessels, to transmigration into tissue, and to eventual dissemination of HIV-infected cells or free virions into tissue.

The presence of specific cytokines and the number and distribution of leukocytes were determined in the retinas of patients with acquired immune deficiency syndrome (AIDS). Using immunohistocytochemical techniques, three retinas from patients with AIDS had focal infiltration by T-lymphocytes and macrophages. These specimens stained positively for tumor necrosis factor-alpha (TNF-alpha) in cells identified morphologically as macrophages and glial cells and showed prominent reactive gliosis. The retinas from seven other affected patients had minimal leukocytic infiltration and no TNF-alpha reactivity; gliosis was present in only one. The retinas from clinically normal patients without human immunodeficiency virus (HIV) contained no TNF-alpha-positive cells. Using in situ hybridization for HIV, four of five patients with AIDS had rare positive cells. No interferon-gamma was detected in any of the retinal tissues tested. These data suggest a role for TNF-alpha in the development of AIDS-related retinal disease.

It has been suggested that aberrant expression of Class II histocompatibility antigens (HLA) is involved in T cell activation and leads to autoimmunity. Although Class II antigen expression was found in various nonlymphoid tissues, including salivary glands, its expression on lacrimal epithelial cells has not been reported. In this study, 12 cadaver lacrimal glands were analyzed for HLA-DR and for the numbers and distributions of T suppressor cells (Ts), T helper cells (Th), B cells, and macrophages. None of these cases exhibited the high numbers of inflammatory cells, tissue damage, and fibrosis characteristic of Sjogren's syndrome. The HLA-DR-positive epithelial cells were detected in ten cases; they represented from less than 1% to more than 70% of the epithelial cells. In these ten positive cases, there were greater numbers of T cells per millimeter squared (229 +/- 94 [mean +/- the standard error of the mean]) than in the two HLA-DR-negative cases (37 +/- 1 [mean +/- range]). Three lacrimal gland specimens tested were negative for immunoglobulin (Ig) G-bearing B cells, and two of the three specimens tested had IgA-bearing cells. Acinar cells were isolated from rat and rabbit lacrimal glands and cultured overnight in serum-free media supplemented with several potential mediators of Class II antigen expression: interferon-gamma, carbachol, or isoproterenol. Freshly isolated cells did not express Class II antigens at detectable levels, but in most experiments, they began to express the antigen even in the absence of putative mediators.(ABSTRACT TRUNCATED AT 250 WORDS)

Frozen brain specimens from eight multiple sclerosis (MS) patients were examined for the presence of leukocytes and their cell products by using a panel of monoclonal antibodies. The results presented here demonstrated that in the MS lesion, there was a marked accumulation of HLA-Dr-positive (Ia-positive) cells. These Ia-positive cells were identified as being glial fibrillary acidic protein positive by using double staining methods. Furthermore, the cells in the MS lesion expressed the interleukin 2 (IL 2) receptor, as identified by the anti-TAC monoclonal antibody. The cells in the region of the plaque also exhibited positive staining with antibodies to IL 1, IL 2, and prostaglandin E. Neither normal brain nor brain specimens from progressive multifocal leukoencephalopathy or Alzheimer's disease showed such patterns of staining. These results suggest that stimulated cells are present in the MS brain, thus implicating an active immune mechanism in the pathogenesis of MS.

The monoclonal antibody anti-Tac, which binds to the interleukin 2 (IL 2) receptor, was used to identify this antigen in human fetal and adult lymphoid tissue. Liver, spleen, thymus, lymph node, and peripheral blood were examined for Tac-positive cells with the use of frozen sections or cytocentrifuge preparations. The results show that cells in the fetal and neonatal thymus express the Tac antigen; these cells are predominantly located in the medulla. The liver and spleen of both fetus and adult exhibit very few Tac-positive cells. Double staining demonstrates that cells bearing the Tac-antigen stain with Leu-4, an anti-T cell antibody. In adult lymph node tissue, the Tac-bearing cells are predominantly distributed in the interfollicular area, with positive cells also present in the germinal center and mantle zone. The Tac antigen is present on both T and B cells. Few Tac-positive cells are present in the circulating peripheral blood.

Human fetal liver was examined during various stages of gestation for the presence of B cells by using immunoglobulin isotype markers and monoclonal B cell antibodies. Frozen sections were studied with the use of single and double staining methods. The B cell monoclonal antibodies used were BA1, which defines both mature and immature B cells; B1, which identifies mature B cells; and B532, which binds to activated mature B cells. The data indicate that both BA1 and mu+ cells are present at 12 wk gestation, and increase in frequency with age. Delta and B1-bearing cells are detected only later in fetal life. Phenotypically identifiable T cells are present at low frequencies in the fetal liver throughout the time period examined (12 to 21 wk). At 12 to 13 wk gestation, the numbers of kappa- and lambda-chain-positive cells are two to three times greater than the number of mu+ cells. Based on morphology and staining with OKM1, these light chain-bearing cells appear to be non-lymphoid, most likely cells of macrophage origin that have phagocytosed maternal IgG. Our results show that the monoclonal antibodies reacting with subsets of B cells in adults can also be used to define distinct subsets of B and pre-B cells in the fetal liver.

The mechanism by which precursor and pre-B cells undergo differentiation is unclear; however, it is known that growth factors play an important role in this maturation process. The lymphokine, IL-4 has been shown to increase expression of class II Ag on B cells and induce B cell proliferation. In the murine system, IL-4 induced differentiation of precursor B cells into pre-B cells. In order to analyze growth factors on B cell development we have established an in vitro culture system for human bone marrow cells. We found that in the presence of IL-4, normal human precursor and pre-B cells can be induced to differentiate in the absence of cell proliferation with four days of culture. Furthermore, IL-4 depressed proliferation induced by supernatant from a T cell line. The differentiation was measured by an increase in both the number of cytoplasmic mu and surface IgM-positive cells. The effect of IL-4 on precursor and pre-B cell differentiation was detected as soon as 14 h of exposure to the lymphokine in the absence of an adherent feeder layer. These data suggest that IL-4 directly affects the differentiation process of normal human precursor and pre-B cells, and may antagonistically affect cell proliferation.

Leprosy is a chronic granulomatous disease with an immunologic spectrum in which lepromatous leprosy patients have defective cell-mediated immune responses, in comparison to tuberculoid leprosy patients. Immunoregulatory aspects of this spectrum were investigated by using monoclonal antibodies to interleukin 2 (IL 2), IL 2 receptors (Tac), and T lymphocyte subpopulations with immunoperoxidase techniques on frozen sections of skin biopsy specimens from 10 tuberculoid and 10 lepromatous patients. A comparison of IL 2+ cells revealed markedly fewer IL 2+ cells in lepromatous specimens (lep. 0.028% +/- 0.02 vs tub. 0.46% +/- 0.28, p less than 0.001). These IL 2+ cells were large, exhibited cytoplasmic staining, and on double immunostaining were Leu-4+, Leu-3a+, Leu-2a-, Tac-, and OKT6-, consistent with the fact they are IL 2 producers. Equivalent numbers of Tac+ cells were observed in both lepromatous and tuberculoid granulomas (lep. 1.5% +/- 0.5 vs tub. 2.1% +/- 0.7, p, NS), suggesting that the responder cells are present in both conditions. The tuberculoid granuloma was highly organized, composed of a central core of mature macrophages, Leu-3a+ and Tac+ cells with a surrounding mantle of Leu-2a+, Leu-3a+, IL 2+, Tac+, and OKT6+ cells. In lepromatous granulomas, Leu-2a+, Leu-3a+, Tac+, and rare IL 2+ cells were randomly admixed with bacilli-laden macrophages. The defective cell-mediated immune responses in lepromatous leprosy appears to be associated with diminished IL 2 production and disorganization of the granuloma.

Sixteen proteins were demonstrated by crossed immunoelectrophoresis (CIE) of Triton X-100 solubilized megakaryoblasts against a rabbit antiserum. One of these reacted with a recently developed monoclonal antibody (SA-1) prepared by immunization with cells from a patient with megakaryoblastic leukemia. Leukemic cells from 8/15 patients with AML stained brightly for this antigen by indirect immunofluorescence. The antiserum also stained a minor subpopulation of myelo-monocytic cells in blood and bone-marrow of healthy individuals, but not lymphoblasts from 5 patients with ALL or cells from 5 CLL patients and 4 non-Hodgkin lymphomas. The protein was shown to be amphiphilic (integral) by charge-shift CIE and hydrophobic interaction CIE with phenyl-Sepharose. It was shown not to be glycosylated by Lentil lectin affinity CIE and by Sodiumborohydride labelling. SDS-polyacrylamide gel electrophoresis of 125I (Bolton-Hunter) labelled, immunoprecipitated material demonstrated 2 bands of molecular weight 34.000 and 46.000 under reducing and non-reducing conditions.

Nonlymphoid tissues from human fetuses ranging in age from 12 to 21 weeks' gestation were examined for the presence of HLA-DR (Ia)-positive cells. Immunoperoxidase staining of cryostat sections revealed Ia-positive cells with dendritic-like morphology, in kidney, heart, pancreas, and lung--but not in brain tissue. These Ia-bearing cells were present at 12 weeks' gestation, and by 21 weeks had increased to substantial numbers in all the organs tested, except for the brain, which remained negative. To further characterize the nature of these Ia-positive cells serial sections were studied with a panel of monoclonal antibodies (MAb) consisting of four reagents identifying monocyte/macrophages and two reagents staining lymphoid cells. The four anti-monocyte/macrophage MAb stained few if any cells in all the tissues examined. Lymphoid cells, as identified by anti-B-cell and anti-T-cell MAb, were also present in very low numbers. Additional studies using a double-staining technique provided direct evidence that the Ia-positive cells bear the human common leukocyte antigen detected by MAb T29 /33 and, with few exceptions, are negative for the macrophage antigen detected by MAb OKM1. The data suggest that nonlymphoid fetal tissues contain Ia-positive dendritic-like cells that are not monocyte/macrophage or lymphoid in origin. These Ia-bearing cells may be related to the dendritic cells found in lymphoid tissues, which are highly stimulatory in mixed leukocyte reactions and are thought to be responsible for the initiation of allograft rejection.

Two-stage stimulation of SK activity of normal human peripheral blood lymphocytes by soluble factors was demonstrated. The first stage was initiated by factors present in supernatant derived from normal B-LCL cultures. Only cell lines which could induce SK activity in culture in an MLR-type reaction had the capacity to produce the active factor. Supernatant factor required adherent cells to cause SK augmentation. The interaction of adherent cells plus supernatant factor resulted in the production of a second soluble factor which stimulated an increase in SK activity in responding lymphocyte populations. This second stage involved a different soluble factor which acted directly on the non-SK, Fc-negative lymphocyte population, and within 3 hr. Data obtained using antisera to interferon (IF) indicated that IF is a component of the second soluble factor, and not of the supernatant factor derived from the B-LCL.

Immunohistologic techniques utilizing monoclonal antibodies have made possible the identification of leukocytes by their phenotypic characteristics rather than by morphologic features alone. A panel of antibodies for T-lymphocyte, B-lymphocyte, and monocyte/histiocyte markers has been applied to frozen sections of nodular sclerosing and mixed cellularity Hodgkin's disease to identify more precisely the various cell types present in tissues involved in Hodgkin's disease. The majority of lymphocytes expressed detectable T-cell phenotypic markers, with a predominance of the "helper" phenotype (Leu 3/OKT4) in most cases. Lymphocytes reacting with anti-B-cell antibodies were also demonstrated; their distribution is described here and has not previously been reported. The anti-B- and anti-T-cell antibodies used in this study failed to give positive reactivity with Reed-Sternberg cells. However, one of the anti-monocyte antibodies (Leu-M1) reacted with diagnostic Reed-Sternberg cells in some cases. The patterns of staining observed varied widely within the two histologic types of Hodgkin's disease, leading to a conclusion that this disease may be more heterogeneous than is currently suspected.

Lymph nodes from 13 cases of reactive hyperplasia were examined with four different monoclonal antibodies to B cells. B-1 recognizes an antigen of 30,000 daltons on B cells. CB-2 was prepared with normal spleen and binds to a glycolipid. BA-1 labels surface immunoglobulin-positive cells, but not T lymphocytes or monocytes. B-532 recognizes an antigenic determinant of 45,000 daltons. Using the immunoperoxidase method on frozen sections of reactive lymph nodes, the staining patterns of these four unique antibodies showed dramatic differences. B-1 labeled 80%-90% of the germinal center cells and 10%-50% of the mantle region. Few interfollicular cells were positive. CB-2 stained predominantly in the mantle area (50%-90% positive cells), with moderate staining in the germinal center as well and less than 1% positive cells in the diffuse cortex. BA-1 exhibited predominant labeling in the mantle (50%-90%), with little staining in the germinal center. A large number of cells in the interfollicular, subcapsular, and medullary regions expressed the BA-1 antigen. The B-5 antibody demonstrated intense staining in the follicle (50%-95%). This staining often appeared to be polarized within the germinal center. The mantle zone demonstrated staining of 30%-50% of the cells. The different staining patterns of the B-cell antibodies, as demonstrated by the in situ distribution of positive cells within the lymph node, may reflect stages of development or activation of the B-cell population.

The peripheral blood cells from a patient with T cell chronic lymphocytic leukaemia were examined for surface marker and functional characteristics. Eighty-91% of the peripheral blood cells formed SRBC rosettes and 22-49% possessed Fc receptors; 73% of the peripheral blood cells were reactive with the OKT8 antiserum and 61% expressed DR antigens. Response to PHA stimulation was markedly reduced, whereas allogeneic responsiveness in mixed leucocyte culture was intact. The ability of Con A-stimulated peripheral blood cells to generate suppressor activity in a mixed leucocyte reaction was deficient, whereas suppression of in vitro immunoglobulin synthesis was greater than normal. The leukaemic peripheral blood cell population expressed a T suppressor phenotype. Functional studies suggest that these cells were derived from the subset of T lymphocytes with regulatory activity for immunoglobulin synthesis as opposed to mitogenic responsiveness.

A cytotoxic monoclonal antibody, CALL1, produced against a human schwannoma tumor was found to react with human platelets, common acute lymphocytic cells (cALL), and lymphoblasts from lymphoid blast crisis of chronic myelocytic leukemia (CML). The hybridoma was repeatedly cloned, and the antibody was considered reactive to a single antigen by absorption tests demonstrating that platelets remove cALL activity and cALL cells absorb platelet activity from the antibody. In addition, chromatofocusing showed that the antibody against platelets and cALL had the same isoelectric point. The CALL1 antibody bound to megakaryocytes but inhibited neither myeloid (CFU-C) nor erythroid (BFU-E) colony formation from bone marrow stem cells. Immunoprecipitation and SDS-gel electrophoresis indicated that CALL1 reacts with a polypeptide of 26,000 daltons.

To evaluate further the immunodeficiency of homosexual men, blood and lymph node specimens were obtained from five homosexual men with lymphadenopathy and from seven homosexual men with Kaposi's sarcoma. Monoclonal antibodies were used to identify T-lymphocyte subsets in blood by cytofluorometry and in frozen sections of nodes by immunoperoxidase techniques. The homosexuals with Kaposi's sarcoma had a T-helper/suppressor ratio in blood of 0.7; the homosexuals with lymphadenopathy had a ratio of 0.6, compared with controls of 2.1. Control lymphoid tissue had a ratio of 3.0 in the interfollicular areas compared with the reactive lymph nodes in the homosexuals with lymphadenopathy, which was 0.7, and nodes from patients with Kaposi's sarcoma, 0.9. The nodes from homosexual men had evident numerous suppressor cells in the follicular center and mantle regions, locations in normal lymphoid tissue where suppressor cells were uncommon.

Peripheral blood leucocytes were examined for the presence of HLA-Dr or Ia-like antigen on the cell surface and in the cytoplasm. Surface staining of viable cell suspensions, using monoclonal anti-Ia antibody in both immunofluorescence and immunoperoxidase methods gave similar results. Using a newly developed immunoperoxidase double staining procedure, which stains the cells when either viable or fixed, both the surface and cytoplasm of the individual cells were labelled and examined. Twenty to thirty percent of the mononuclear cells were positive for Ia staining on the cell surface and in the cytoplasm. Morphologically these positive cells were identified as both lymphocytes and monocytes. A small percentage (5-9%) of these monocytes and lymphocytes consistently labelled only cytoplasmic Ia determinants. In contrast, only surface binding was observed with monoclonal antibodies recognizing T cell subpopulations. The ability to detect intracellular Ia antigenic determinants is of value in distinguishing stages of lymphocyte and monocyte development.