anti-CD3 MoAb Research Articles

Abstract # 3177 Early infant institutionalization leads to a premature accumulation of terminally differentiated CD57 + T cells by adolescence

Early rearing conditions can exert a strong influence on the immune system, affecting regulation and the capacity to respond effectively to pathogens. Most PNI research focuses on inflammatory processes, but the absence of typical parenting can also result in a polarization of T cells. An optimized multicolor immunophenotyping panel was used to enumerate T cell lineages, comparing adolescents who had spent 1–2 years in an orphanage to typically raised teenagers. This presentation will focus primarily on CD4 + CD57 + and CD8 + CD57 + cells, further subdivided into naive, central memory and effector/memory subsets, including cells in the terminally differentiated state. As compared to family-reared American teenagers, the adopted adolescents, especially males, had significantly more TEMRA cells. High frequencies of this cell population are normally associated with aging and immune senescence in older adults, resulting in a lower homeostatic capacity. They also reflect sustained activation and participate in containing latent Herpes viruses. Institutional rearing during infancy was associated with a greater likelihood of being CMV seropositive, which contributed to, but did not entirely account for the persistent effects of early rearing on T cell profiles in male adolescents. Our analysis also found that rearing conditions affected cytokine responses to several T cell and inflammatory stimulants in culture. Following overnight stimulation of whole blood with PHA, LPS, IO/PMA, or anti-CD3/anti-CD28 MoAB, cytokine concentrations were determined by multi-analyte electrochemiluminesence array.

The Effect of Granulocyte-Colony-Stimulating Factor (G-CSF) on T Cell Polarization in Vitro: A Direct Comparison Between Nivestim® and Neupogen®

Introduction Recombinant granulocyte colony stimulating factor (G-CSF) such as filgrastin (NeupogenÒ) is widely used to mobilize peripheral blood stem cells (PBSC) in healthy donors prior to allogeneic stem cell transplantation (all-SCT). In comparison to the bone marrow harvest, the G-CSF mobilized graft has a higher content of donor-derived T cells, the primary mediators of acute graft versus host disease (aGvHD). However, the incidence of aGvHD is identical suggesting a modulatory effect of Neupogen on T cells. The differentiation of allo-T cells to a T-helper 1 (Th1) phenotype polarizes the cells to produce IFN-g and IL-2, and this in turn promotes the development of GvHD. Conversely, recent evidence suggests that T-helper 2 (Th2) cells that produce IL-4 and IL-10 protects against GvHD. In healthy donors, G-CSF (NeupogenÒ) has been shown to decrease IFN-g and increase IL-4 production. A finding that is also observed under specific stimulatory condition in vitro.The recent patent expiry on G-CSF (Neupogen®) has prompted the development of alternative forms of G-CSF – called biosimilars. These molecules are structurally equivalent but their biological mode of action is currently under review. However, biosimilar G-CSF has not been accepted for routine stem cell mobilization in healthy donors primarily due to a lack of data about their safety in this cohort. In addition, no data exists of their influence on T cell modulation, which will potentially have a significant effect on aGvHD in the recipient. The primary objective of this study was to investigate the in vitro effects of Nivestim®, a biosimilar G-CSF that has been approved by the Therapeutic Goods Administration in Australia, and compared to the reference product filgrastim (Neupogen®) on human CD4+ T cells obtained from healthy volunteers.Results PBMC from 10 healthy volunteers, were cultured in the presence of Nivestim® or Neupogen® (both at 100 ng/ml), and stimulated 24 hrs later with either (1) anti-CD3 MoAb; (2) Phytohaemagglutin (PHA) or (3) PMA plus Ionomycin. The effects of Nivestim® and Neupogen® were examined on Th1 and Th2 cytokine profiles (IFN-g and IL-4 respectively), Th-specific transcriptional regulators, and T cell proliferation and survival.Our findings showed that CD4+ T cells from PBMC cultures produced significant levels of IFN-g following T cell activation. However, in the presence of Nivestim® or Neupogen®, the production of IFN-g was notably reduced and IL-4 levels were increased. These findings were consistent regardless of whether the T cell receptor was stimulated directly, or by-passed through the activation of proximal signaling molecules.Conclusion Whilst this pattern of Th2 polarization was not observed for all healthy volunteers, the biological effects of Nivestim® was comparable to Neupogen® in all cases. These findings have established that Nivestim® has an immunomodulatory effect on Th1/Th2 polarization in vitro that is equivalent to the reference product Neupogen®. Our findings will assist in facilitating Nivestim’s use for stem cell mobilization in healthy donors. DisclosuresMifsud:Hospira: Research Funding. Ismail:Hospira: Research Funding. de Valle:Hospira: Research Funding. Spencer:Hospira: Research Funding. Patil:Hospira: Research Funding. Grigoriadis:Hospira: Research Funding. Gugasyan:Hospira: Research Funding.

Dendritic Cell Vaccination in Acute Leukemia Patients Induces Reduction of Myeloid-Derived Suppressor Cells : Immunological Analysis of a Pilot Study

Background and Purpose: Myeloid-derived suppressor cells (MDSC) are a heterogeneous cell population that have an immunesuppresive function and play an important role in tumor immunology and self tolerance. Elevated levels of MDSCs in peripheral blood (PB) are reported in various cancers and hematological malignancies such as MDS, NHL and MM. We reported that vaccination with Wilms’ tumor 1 (WT1) peptide-pulsed dendritic cells (DC) in NHL patients induced not only WT1 specific immune responses but also innate immunity which correlated with clinical efficacy (ASH 2013). In the present study, we focused on MDSCs and investigated the effects of DC vaccination on the alteration of MDSCs which have negative influence on disease progression.Patients and Methods: 8 patients with acute leukemia (6 AML and 2ALL patients; aged 16-77) who were treated with WT1 peptide-loaded DC vaccination were enrolled in the present study. MDSCs were analyzed by FACS. Linage negative, CD11b+CD33+HLA-DR- cells were defined as MDSC. Monocytic and granulocytic MDSC were defined as CD14+HLA-DRlow/- and CD15+CD11b+CD33+HLA-DR-, respectively. For proliferation assay, CD14+DR- cells and CD3+ T cells were isolated by magnetic beads method. CFSE-labeled CD3+ T cells were stimulated with anti-CD3 and anti-CD28 moAb together with IL-2 in the presence or absence of CD14+DR-cells for 4 days and cell division was analyzed by FACS. Cytoplasmic staining of indoleamine 2,3-deoxygenase (IDO) and arginase 1 were performed by permeabilization using saponin followed by moAb staining. Arginase 1 protein levels in plasma was assessed using a commercially available ELISA kit.Results: 3 patients were in complete remission (responder) and 5 others were in disease progression (non-responder) following one course of vaccination. WT1 specific T cell responses evaluated by a HLA-tetramer assay and a delayed type hypersensitivity (DTH) test were observed in all the responders and 2 non-responders. Mean percentage of MDSCs, monocytic and granulocytic MDSCs in PB was higher in acute leukemia patients than in healthy donors (1.60±0.72%, 16.56±6.07%, 1.34±0.69%, respectively in patients; 0.60±0.31%, 13.1±4.1%, 0.37±0.1%, respectively in healthy donors). Absolute number of circulating monocytic and granulocytic MDSCs before and after vaccination in responders was 359.4±117.8/μl and 35.2±14.8/μl, 282.8±119.2 /μl and 14.4±12.0/μl, respectively. On the other hand, those in non-responders were 126.3±60.2/μl and 36.3±21.7/μl, 181.3±124.0/μl and 65.1±12.0/μl, respectively. While DC vaccination resulted in reduction of both monocytic and granulocytic MDSCs by 21.3% and 59.1%, respectively in responders, it induced augmentation of these MDSCs by 43.5% and 79.3%, respectively in non-responders. A portion of MDSCs expressed IDO and arginase 1 in cytoplasm. While the percentage of IDO positive cells in monocytic MDSCs increased by 2.2 and 2.3 times in responders and non-responders, respectively following vaccination, the positivity of arginase 1 decreased by 59% in responders. On the other hand, the positivity of IDO and arginase 1 in granulocytic MDSCs decreased at the same level in both responders and non-responders following vaccination. CD14+DR-cells inhibited the proliferation of CD3+ T cells in a dose dependent manner, indicating that these cells share characteristics of MDSCs. The inhibition of the proliferation of CD3+T cells was partially restored by the addition of 1-methyl-DL-tryptophan (IDO inhibitor) and Nω-hydroxy-nor-arginine (arginase 1 inhibitor), suggesting that the inhibition was mediated at least in part by IDO and arginase 1. Amount of arginase 1 in the plasma before and after vaccination decreased by 25% in responders, not in non-responders.Conclusions: These results demonstrated that DC vaccination resulted in the reduction of the absolute number of MDSCs which seems to be correlated with clinical efficacy. DC vaccination may have inhibitory effects on several functions of MDSCs that can suppress immune surveillance against leukemia, which is favorable for regression of leukemia cells. DisclosuresNo relevant conflicts of interest to declare.

Functional Analysis and Gene Expression Profile of Umbilical Cord Blood Regulatory T Cells.

Abstract 4085Poster Board III-1020 IntroductionUmbilical cord blood (CB) stem cells are now broadly used in the unrelated stem cell transplant setting and comparative studies with different stem cell sources have shown that CB transplant is characterized by a lower risk of graft-versus-host disease (GVHD). The immaturity of CB T cells has been generally regarded as the main contributing factor accounting for this phenomenon; the possible role played by CB regulatory T cells (Tregs) for the suppression of the allogeneic T-cell response is now under investigation, but very scare data are so far available. Aim of this study was to analyze and compare the functional properties and the gene expression profile of Tregs expanded from CB units with those expanded from the peripheral blood (PB) of adult normal donors. MethodsTregs were purified from mononuclear cells obtained from 23 CB units and from the PB of 13 adult normal donors using the CD4+CD25+ regulatory T-cell isolation kit (Miltenyi Biotec) and expanded for 6 days in 96-well U-Bottom plates coated with the anti-CD3 (5 ug/ml) and anti-CD28 (5 ug/ml) MoAbs in the presence of IL-2 (100 U/ml). Immunophenotypic analyses were performed before and after expansion. To assess their suppressive functions, expanded Tregs were seeded with autologous effector T cells stimulated with allogeneic dendritic cells (DC) pulsed with apoptotic leukemic blasts, then incubated with [3H]-thymidine and counted in a beta-counter. Suppressor activity was measured as [3H]-thymidine incorporation in the presence or absence of Tregs. The IL-10 production capacity of expanded Tregs was tested using an ELISA assay. The two-sided student t test was used to evaluate the significance of differences between groups. Gene expression profile experiments were performed using the HGU133 Plus 2.0 arrays (Affymetrix); statistical analyses were carried out using the dChip software; a t test was used to evaluate the presence of specifically expressed classes of genes. Functional annotation analysis was performed using the DAVID software. ResultsCB and PB Tregs presented similar immunophenotypic appearances before and after expansion. Im particular, after expansion they presented a comparable expression of surface CD4, CD25, CD62L, CCR5 and CD45RO, and of cytoplasmic CTLA-4 and Foxp3, while they both were negative for the CD45RA antigen, thus indicating the loss of their naïve features. On the contrary, Tregs obtained from CB (n=23) presented a much higher expansion capacity compared to those obtained from PB (n=13): mean fold increase (range), CB 10.3 (1.6-24), PB 3.9 (1.5-10), p 0.003. CB expanded Tregs (n=6) exerted a potent suppressive function on the proliferative reaction of T cells stimulated by allogeneic DC, that resulted inferior even though not significantly compared to that exerted by PB expanded Tregs (n=5): mean fold reduction (range), CB 7.8 (2.5-15.1), PB 14.3 (1.5-23.7), p 0.14. Tregs expanded from CB (n=4) and PB (n=1) presented a high and comparable in vitro IL-10 production capacity: mean pg/ml (range), CB 326.5 (226-426), PB 382. Gene expression profile analysis showed a higher number of upregulated genes in Tregs expanded from CB (n=2) compared to Tregs expanded from PB (n=3); among them, a significant enrichment of genes involved in cell proliferation, cell cycle checkpoints, signal transduction, cell differentiation, apoptosis, TGF-β receptor pathway and the GrNH pathway was observed. This suggests that CB Tregs retain a more undifferentiated program and are characterized by the high expression of genes which might provide an advantage in cell expansion. Finally, when looking at the Foxp3 gene expression levels, no difference was observed between the two populations. ConclusionsThese results demonstrate that Tregs contained in CB retain an expansion potential superior to that of Tregs isolated from the PB of normal donors, as confirmed by functional analyses and gene profile. Tregs expanded from CB and PB seem to exert a potent and comparable suppressive function of the proliferative effect in mixed lymphocyte reaction assays. The maintaining of the modulatory properties after expansion is confirmed by the expression of the Foxp3 gene and protein, and by the production of IL-10. These data offer further insights into the understanding of the biology of CB transplantation indicating a possible role played by CB Tregs in the suppression of the allogeneic T-cell response. Disclosures:No relevant conflicts of interest to declare.

Identification of Novel Cryptic Chromosomal Abnormalities in Primary Myelofibrosis by Single-Nucleotide Polymorphism Oligonucleotide Microarray.

Abstract 1890Poster Board I-913 Background.Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm (MPN) characterised by a proliferation of predominantly megakaryocytes and granulocytes in bone marrow that in fully developed disease is replaced by fibrous tissue.At molecular level, no specific defect has been identified yet. Cytogenetic abnormalities occur in up to 30% of patients, the commonest including del(13)(q12-22), der(6)t(1;6)(q21-23;p21.3), del (20q), and partial trisomy 1q. In addition, approximately 50% of patients with PMF exhibit a single, recurrent, somatic mutation in the gene encoding the cytoplasmic tyrosine kinase Janus kinase 2 (JAK2). However, such mutation is not specific, also occurring in other MPN.Recently a couple of reports dealt with single-nucleotide polymorphism (SNP) array karyotyping of MPD, including some PMF. Importantly, such studies could identify previously uncovered genetic lesions, highlighting the importance of novel high resolution technologies for the detection of formerly unknown, cryptic aberrations.In this study we performed high resolution karyotyping by SNP oligonucleotide microarray by using the most updated Affymetrix array (Genome-Wide Human SNP Array 6.0) in 20 cases of myelofibrosis (MF) in order to identify novel cryptic genomic aberrations. Methods.DNA (500 ng) was extracted from peripheral blood cells (PBMNC) of 14 primary and 6 secondary MF patients. PBMNC were depleted from lymphocytes by magnetic beads. Briefly, CD3+ cells were labeled with anti-CD3 MoAb directly coupled to magnetic microbeads (Miltenyi Biotech), washed and subsequently purified using Mini-MACS technology. After selection, cell present in the positive (CD3) and negative (PBMNC) fractions were counted and submitted to flow cytometry analysis. DNA was processed and hybridized to the Affymetrix SNP arrays 6.0 as for manufacturer instruction. A whole-genome copy number variation (CNV), genotyping, loss of heterozygosity (LOH) and uniparental disomy (UPD) analyses were performed using the Partek Suite 6.0. Ten lab-specific as well as 90 HapMap samples relative to Caucasian healthy donor were used as control reference. Genomic abnormalities were defined as recurrent when occurring in at least 25% of cases.JAK2 mutational status was assessed as reported, by alle-specific PCR. Clinical information and complete follow up were retrieved for all cases.Direct sequencing, FISH, qPCR and immunohistochemistry (IHC) has been chosen for validation. Results.In all patients we could detect several CNV. The median number of CNV was 60 (range, 34-72), including 46 amplifications (A) and 14 deletions (D). All commonest previously described abnormalities were detected. In addition, several formerly uncovered recurrent lesions were identified, mainly involving 1p, 1q, 2p, 4p, 4q, 5q, 6p, 6q, 7q, 8p, 9q 10q, 11p 11q, 12p, 14q, 15q, 16p, 16q, 17q, 18q, 19q, 20p, 22q. The median size of such CNV was 424,582 Kbp (1,379 Kbp-71,277 Mbp).We then compared JAK2+ vs. JAK2− cases. Of note, we found numerous definite aberrations (A or D) distinguishing the two groups and specifically affecting 16q23.1, 1p36.13, 3q26, 14q13.2, 5q33.2, 6q14.1, 7q33, 8p23.1, and 9p11.2.Grippingly, several genes of potential interest for PMF pathogenesis were identified within the involved loci, including RET, SCAPER, WWOX and SIRPB1. Among others, the product of such genes has been selected for validation by IHC. Similarly, many miRNA were recognized, which may deserve further investigation. Conclusions.By using a newly developed highly sensitive array we identified novel cryptic lesions in patients affected by MF. Future studies on larger series, as well as functional analyses will definitely assess their role in the pathogenesis of the disease. Of note, consistent differences were recorded in JAK2+ vs. JAK2−, supporting the hypothesis of different genetic mechanisms occurring in the two sub-groups. Acknowledgments:this work was supported by AIL Pesaro Onlus, Centro Interdipartimentale per la Ricerca sul Cancro “G. Prodi”, BolognAIL, AIRC, FIRB, RFO, Fondazione Cassa di Risparmio in Bologna, Fondazione della Banca del Monte e Ravenna, Progetto Strategico di Ateneo 2006.*GV and MRS equally contributed to this work. Disclosures:No relevant conflicts of interest to declare.

CD4+ T cell-mediated fatal hyperinflammatory reactions in mice infected with Penicillium marneffei

SUMMARY In the present study, we demonstrate that all mice survived when a low dose of Penicillium marneffei was instilled intratracheally, while severe infection induced by instillation of 1 ×108 and 1 ×107 colony-forming units (CFU) killed all and 50% of mice, respectively, within 14 days, although the number of live microorganisms in the lungs of these animals was found to decrease with time. The cellular inflammatory responses in the lungs were much more striking in mice with severe infection than in animals infected with a low dose of microorganisms. The number of leucocytes, macrophages, neutrophils and lymphocytes in the lungs increased progressively during infection, and were more than 50 times higher on day 11 than in the control count. CD4+ T cells were the predominant cells in the lungs, and played an important role in hyperinflammatory host reactions, because neutralizing anti-CD4 MoAb increased the survival rate in infected mice despite the presence of a high number of live microorganisms in the lungs. Our results indicate that severe infection with P. marneffei induces fatal hyperinflammatory host reactions, mediated to a large extent by CD4+ T cells, although the infection is well controlled. However, the contribution of endogenous tumour necrosis factor-alpha (TNF-α) remains unsubstantiated, since administration of neutralizing anti-TNF-α MoAb in the present study failed to prolong survival in infected mice.

Isotype-specific cross-linking of select human Fc gamma R isoforms triggers release of IL-6.

Anti-CD3 MoAbs are widely used in T cell activation studies, and are effective in immunosuppressive therapy. We used a panel of mouse (m) anti-CD3 switch variant MoAbs of five different isotypes to study IL-6 release from accessory cells. Incubation of human (h) mononuclear cells with anti-CD3 MoAbs resulted in increased IL-6 levels with MoAbs of mIgG1 and mIgG2a isotypes, with no effect of mIgG2b or mIgA. This suggested involvement of IgG Fc receptors (Fc gamma R) in triggering IL-6 production. To evaluate the role of different Fc gamma R molecules individually we used a panel of hFc gamma R-transfected mouse fibroblasts, and Jurkat T cells as a model. IL-6 secretion by CD32 transfectants expressing the hFc gamma RIIa high-responder (HR) allelic form was triggered by mIgG1 anti-CD3 MoAb, with no effect of four other isotypes. None of the anti-CD3 MoAbs induced IL-6 secretion by CD32 transfectants expressing either a variant of this receptor, containing only a single intracellular amino acid (CT-), the hFc gamma RIIa low-responder (LR) allelic form, or hFc gamma RIIb1. hFc gamma RI (CD64) transfectants exhibited IL-6 production after incubation with mIgG2a anti-CD3 MoAb, and to a lesser extent with mIgG2b, and mIgG1 MoAb. Indirect involvement of T cells in triggering IL-6 secretion could be excluded by experiments in which transfectants were cultured with immobilized anti-CD3 MoAb. These data indicate that cross-linking of either hFc gamma RI, or hFc gamma RIIaHR by appropriate anti-CD3 MoAbs triggers IL-6 production of accessory cells, and not T cells. This may also take place in vivo during immunosuppressive therapy with anti-CD3 MoAbs, and related antibody-mediated immune responses.

Signalling via CD28 of human naive neonatal T lymphocytes.

Accessory molecules play a crucial role in the development of the T cell response to antigenic challenge. We have examined the role of CD28 in modulating the 'naive' neonatal T cell response to anti-CD2-mediated activation. To compare the role of CD28, neonatal and adult T cells were stimulated with a pair of mitogenic anti-CD2 antibodies in the presence or absence of anti-CD28 MoAb. With anti-CD2 alone, neonatal T cells proliferated slightly but produced no detectable IL-2, whereas adult T cells proliferated vigorously, with significant IL-2 production. Costimulation with anti-CD28 MoAb greatly enhanced the proliferative response of neonatal T cells to levels equivalent to those of adult T cells, whereas adult T cells showed only slight increases. Although IL-2 secretion was increased in the presence of anti-CD28 MoAb, neonatal T cell IL-2 production remained lower than in adults. In contrast, enhancement of IL-2 mRNA expression in neonates was similar to adult levels. Anti-CD28 MoAb costimulation increased NF kappa B levels in neonates, albeit to levels lower than that of adults. The cellular mechanism governing the diminished proliferative response of neonatal T lymphocytes to anti-CD2 may therefore be due to decreased NF kappa B induction, reduced IL-2 mRNA expression and deficient IL-2 production. Although anti-CD28 MoAb costimulation enhances all of the above signals, NF kappa B and IL-2 levels remain lower than in adults, suggesting the need for further activation requirements in the neonate.

Effects of anti-CD3 monoclonal antibodies on functional activity of lymphocytes: studies in vivo and in vitro.

Lymphocyte functional activity was tested in 38 renal transplant recipients receiving induction treatment with various anti-CD3 MoAbs, i.e. OKT3, T3.G2a (an IgG2a anti-CD3 MoAb) or T3.A (an IgA anti-CD3 MoAb of the same idiotype). During treatment with OKT3 and T3.G2a, lymphocyte response to phytohaemagglutinin-P (PHA), as determined with the use of a whole-blood lymphocyte culture technique, decreased significantly. However, during treatment with T3.A PHA response was not affected. Using a conventional lymphocyte culture technique, PHA response was unchanged during treatment with all three MoAbs, indicating that the immunosuppressive effect of OKT3 and T3.G2a is probably dependent upon the presence of MoAb in culture medium and is reversible. In addition, we tested in vitro inhibition of aspecific mitogen- or antigen-induced lymphocyte stimulation by OKT3, T3.A and T3.G2a. It appeared that at low concentrations (< 25 ng/ml) T3.G2a and OKT3 exerted a stronger immunosuppressive effect than T3.A. However, at higher concentrations T3.A, OKT3 and T3.G2a were equally immunosuppressive. We conclude that the immunosuppressive effect of T3.A is caused by blindfolding. At low concentrations T3.G2a exerts its immunosuppressive effect mainly through modulation of the CD3 and/or T cell receptor complex, as a result of interaction with Fc receptors on monocytes. At higher concentrations blindfolding of the CD3/T cell receptor complex may contribute to immunosuppression.

Lymphocyte changes associated with prolongation of cardiac allograft survival in adult mice using anti-CD4 monoclonal antibody.

This study investigated the effect of anti-CD4 MoAb treatment on lymphocyte phenotype and function and correlated these changes with the prolongation of cardiac allograft survival in adult mice. Indefinite survival of heterotopic cardiac allografts was obtained in several fully allogeneic strain combinations when two doses of the anti-CD4 MoAb, YTS 191.1, were given at the time of transplantation. A dose response analysis in the C57BL/10 to C3H/He strain combination showed that very low doses of YTS 191.1 (25 micrograms/dose) were able to induce prolonged allograft survival when administered perioperatively. At the time of transplantation the immunosuppression induced by administration of the anti-CD4 MoAb is not antigen-specific, as heart grafts from different donor strains, mismatched for both major and minor histocompatibility antigens, showed prolonged survival in treated recipients. Immunocompetence was restored by 6 weeks after MoAb treatment, as recipients regained the ability to reject a cardiac allograft transplanted at this time point. However, while recovery of immunocompetence could be demonstrated in vivo, leucocytes isolated from the peripheral lymphoid organs of treated mice continued to be hyporesponsive in mixed leucocyte culture (MLC). Phenotypic analysis of the peripheral lymphoid tissues showed that C3H/He recipients treated with 25 micrograms/dose of YTS 191.1 had a marked, but not complete, elimination of the CD4+ subset at the time of transplantation, which was gradually restored to 50% of normal by 6 weeks after treatment. Thus, complete elimination of the CD4+ subset was not required to achieve indefinite allograft survival, and immunocompetence, as assessed in vivo, returned even when the CD4+ subset was present at half the normal level. Low doses of anti-CD4 MoAb (25 micrograms) had no effect on the expression of the CD4 molecule by thymocytes, and yet thymocytes were hyporesponsive to alloantigen in vitro. At higher doses of YTS 191.1, immature CD4+8+ thymocytes were selectively depleted. These results suggest that anti-CD4 MoAb therapy may modulate the intrathymic T cell selection process. These studies provide further insight into the mechanism of action of low dose, depleting anti-CD4 MoAb therapy in allograft rejection, and form a basis from which rational modifications to therapeutic protocols in transplantation models can be made.

Defective functional response to membrane stimuli in lymphocytes from patients with benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a local disturbance in the prostate that may involve an inflammatory infiltrate predominantly composed of activated lymphocytes and macrophages. The activation and proliferative response of T lymphocytes to different mitogenic signals has been analysed in peripheral blood mononuclear cells (PBMC) from 45 patients with BPH and 55 healthy controls. The PBMC obtained from the patients showed a significant specific impairment in proliferation, CD25 expression and IL-2 production in response to stimulation with lectins (phytohaemagglutinin (PHA), concanavalin A (Con A)), that was not corrected by the addition of IL-2 or of phorbol esters (phorbol myristate acetate (PMA)). Also, the CD28 response was defective in patient PBMC. Activation with anti-CD3 or anti-CD2 MoAbs was normal, but the addition of PMA to these stimuli provoked a significant defective response. Only the use of transmembrane stimuli (PMA and ionomycin) elicited responses similar to those found in the control group. The results indicate that peripheral T lymphocytes from BPH patients show a functional impairment that is mainly explained by an alteration of membrane signals (PHA, CD28) and is distal to protein kinase C (PKC) activation.

Effects of activin A on IgE synthesis and cytokine production by human peripheral mononuclear cells.

Activin A not only stimulates the synthesis and release of pituitary follicle-stimulating hormone, but exerts various effects on haematopoietic cells, embryos, and fibroblasts. In the present study we have examined effects of activin A on IgE synthesis and cytokine production by peripheral blood mononuclear cells (PBMC) in normal humans. When PBMC were cultured in the presence of IL-4, activin A significantly augmented IgE production induced by IL-4. Activin A did not affect, however, IgE production from highly purified B cells when they were stimulated with anti-CD40 MoAb and IL-4. The fact that in the latter condition IgE synthesis was T cell- and monocyte-independent indicated that activin A does not directly influence B cells for IgE synthesis. Rather, production as well as gene expression of IL-6, which is known to enhance IgE synthesis by purified monocytes, was induced by activin A alone. In addition, activin A induced other monokines such as IL-1 and tumour necrosis factor (TNF)-alpha from monocytes. In contrast, activin A neither induced nor augmented the production of TNF-beta or interferon-gamma (IFN-gamma), both of which are known to be exclusively generated by T cells. These data indicate that activin A plays a certain role in physiological functions for monocytes in normal humans.

Inhibition of IL-4 receptor up-regulation on B cells by antisense oligodeoxynucleotide suppresses IL-4-induced human IgE production.

IL-4 is shown to up-regulate its own receptor (IL-4R) on human lymphocytes, but the functional significance of up-regulated IL-4R is not clear regarding IgE production. This study investigated the possible role of IL-4-induced up-regulation of IL-4R on B cells in the induction of human IgE synthesis by means of antisense strategy. Among three antisense oligodeoxynucleotides designed against the downstream of translation initiation site of IL-4R cDNA, S-oligo 1, complementary to nucleotide 1-24, showed the strongest inhibition of the constitutive expression of IL-4R on Daudi cells. Addition of S-oligo 1 together with IL-4 also decreased the up-regulated but not constitutive levels of IL-4R on peripheral blood B cells without affecting the concomitant enhancement of CD23, CD40, HLA-DR and surface IgM expression, indicating that its effect is specific for IL-4R up-regulation. When S-oligo 1 was added to B cells costimulated with IL-4 and anti-CD40 MoAb, it induced a dose-dependent inhibition of IgE production. This inhibition was accompanied by a decrease in the expression of mature C epsilon transcripts, whereas the accumulation of germ-line C epsilon transcripts was not affected by S-oligo 1. These data suggest that the signal transduction mediated by the up-regulated IL-4R on B cells may be intimately associated with the induction of isotype switching to IgE that leads to mature C epsilon transcription and IgE production.

Study of induction of activation of human peripheral blood mononuclear cells with a non-activating form of anti-CD3 MoAb in autoimmune thyroid disease (AITD).

Anti-CD3 (OKT3) MoAb is a mitogenic agent which activates lymphocytes. We have studied the effects of murine anti-human OKT3 MoAb (IgG1) alone or in combination with IL-2, human thyroglobulin (Tg) and thyroperoxidase (TPO) antigens on the proliferation of whole peripheral blood mononuclear cells (PBMC) (including monocytes) or subtypes (T, CD4+, CD8+, B) as measured by tritiated thymidine (3H-TdR) incorporation. B cell differentiation was studied by measuring numbers of IgG-secreting cells and specific anti-TPO/anti-Tg-secreting cells by SPOT ELISA. PBMC or lymphocyte subtypes, obtained from 45 patients with Hashimoto's thyroiditis (HT), 40 Graves' disease (GD) and 51 normal controls were cultured in 96 microtitre plates for 6 days in the presence of OKT3 MoAb at final concentrations 25-250 ng/ml, IL-2 15 U/ml, Tg and TPO (1 micrograms/ml). Then cultures were pulsed with 0.2 microCi 3H-TdR/well and incorporation was measured after 18 h. IgG and anti-TPO/Tg-secreting cells were detected at 7 days. Higher proliferative responses from whole PBMC preparations in response to any of the combinations including OKT3 MoAb were observed in the HT preparations, while the basal values were the lowest. IL-2 alone increased these responses markedly, but equally in all groups. IL-2 in combination with OKT3 had an additive effect on proliferation, with higher responses in HT. Tg and TPO antigens did not change these responses. Most HT preparations responded with their maximum proliferation to the lowest concentration of OKT3 MoAb (25 ng/ml), whereas in GD and control preparations of PBMC these responses were shifted to higher concentrations (250 ng/ml); even with those, proliferation was not so enhanced in controls when compared with HT and GD preparations. In contrast, the proliferative responses of T cells alone and subpopulations of CD8+ suppressor/cytotoxic cells were decreased in HT preparations compared with controls. Monocytes were necessary for proliferation. In the subpopulation of B cells (> 95% pure) and CD4+ helper/inducer cells, differences did not reach significance. In spite of the effect on proliferation, OKT3 MoAb only mildly but significantly increased the numbers of IgG-secreting cells in HT and GD preparations and did not stimulate synthesis of specific antibodies. Our data suggest that the increased proliferative responses of whole PBMC to OKT3 MoAb in HT preparations might be due to insufficient activation of T suppressor/cytotoxic cells.

The cytotoxic analysis of T cell receptor V delta 1+ T cell lines derived from the synovial fluid of rheumatoid arthritis patients.

We established six human T cell lines derived from rheumatoid arthritis synovial fluid (RASF). Phenotypically, T cell receptor (TCR) gamma delta T cells occupied the majority of these lines and most of them expressed the TCR V delta 1 molecule. In contrast, V delta 2+ T cells, the majority population of peripheral blood gamma delta T cells, were rarely detected in these lines. To study the immunobiological roles of RASF V delta 1+ T cells in RA development, their cytotoxic profile was studied. The results showed that these T cells selectively lysed Daudi, but not K562 cells. The cytotoxic response was MHC-unrestricted, and was inhibited by anti-CD3 MoAb. Moreover, the cold target inhibition assay showed that the cytotoxicity was competitively inhibited by autologous and allogeneic primarily cultured RA synovial cells as well as synovial sarcoma and chondrosarcoma lines. However, PBL did not inhibit this cytotoxicity. These data suggest that V delta 1+ T cells in RASF may recognize the antigen which is commonly expressed on the surface of Daudi and the cells derived from RA synovium. We can assume that the cytotoxic V delta 1+ T cells are selectively expanded in RASF, playing a significant role for the pathogenesis of certain RA cases.

B7/BB1 provides an important costimulatory signal for CD3-mediated T lymphocyte proliferation in patients with systemic lupus erythematosus (SLE).

Successful T cell activation via the T cell receptor (TCR)/CD3 complex requires at least one contact-dependent second signal delivered by costimulatory molecules, including the B7/BB1 molecule, that are present on antigen-presenting cells (APC). SLE is characterized by multiple complex lymphocyte abnormalities of undefined molecular origin. It is currently unclear whether an intrinsic defect of T cell or an underlying APC dysfunction is responsible for defective in vitro proliferation of T cells from patients with SLE. We planned the present experiments to ask whether the TCR/CD3-mediated and B7/BB1-costimulated T cell proliferation is normal in these patients. We used enriched T cell populations that were stimulated with an anti-CD3 MoAb in the presence of controlled quantities of functional B7/BB1 antigen. Freshly isolated T cells from 17 SLE patients (10 and seven patients with either active or inactive disease, respectively) and 11 normal individuals were cocultured with irradiated B7/BB1-transfected P815 cells or parental P815 cells in the presence of OKT3 MoAb at optimal and suboptimal concentrations for 2.5-7 days. Normal or SLE T cells responded similarly to stimulation via anti-CD3, in the absence of B7/BB1 antigen. A several-fold increase in T cell proliferation in the presence of B7/BB1 antigen was observed. Proliferation was inhibited in the presence of anti-B7/BB1 MoAb, but not with control MoAbs. Interestingly, dose-response curves and time kinetics of B7/BB1 costimulation were similar in T cells from patients with either active or inactive SLE at the time of study, and normal individuals. In addition, no differences in the IL-2 receptor release by T cells cultured under these conditions were observed between SLE patients and normal individuals. These results demonstrate that CD28 signalling is not intrinsically impaired in patients with SLE; further studies to investigate whether abnormal B7/BB1 expression is involved in the autoimmune process are needed.

HIV-specific lymphoproliferative responses in asymptomatic HIV-infected individuals.

In vitro lymphoproliferative responses to HIV-1 recombinant antigens (gp160, p24, and Rev protein) were studied in 83 patients with asymptomatic HIV-1 infection (CDC groups II and III) and circulating CD4 lymphocyte numbers > 400/mm3. Significant response to at least one of the three antigens was detected in 52.4% of the subjects, but the responses were weak, and concordance of the response to the three antigens was rare, the frequency of individuals responding to each antigen not exceeding 22.4%. Increasing frequencies of response were observed when recall antigens (tetanus toxoid and Candida albicans glycomannoprotein) (65.5%) and anti-CD3 MoAb (76.6%) were used as stimuli. Although a significant association between lymphocyte response to p24, but not gp160, and steadiness of CD4 lymphocyte numbers before the assay was observed, no predictive value for lack of CD4 cell decrease was confirmed for either antigen, and fluctuation of the responses to HIV antigens was seen during subsequent follow up. The panel of T cell assays used could be regarded as appropriate for monitoring both HIV-specific responses and T lymphocyte function during immunotherapy with soluble HIV antigens.

Association of T cell and macrophage dysfunction with surface gp 120-immunoglobulin-complement complexes in HIV-infected patients.

The mechanism of CD4+ cell depletion and functional T helper cell inhibition in HIV-infected individuals is poorly understood. The present study demonstrates that immune complex-covered CD4+ cells are associated with T cell inhibition and macrophage stimulation. We studied 30 patients with ARC/AIDS and 35 asymptomatic HIV+ haemophilia patients. Overall, 20 +/- 3% of peripheral CD4+ lymphocytes were covered with gp120 (range 0-94%). gp120+ cells also exhibited surface-bound IgG (P = 0.0001), IgM (P = 0.0001), and complement (P = 0.0001). Decreased in vitro lymphocyte proliferation was associated with the immune complex load of CD4+ cells. The higher the percentage of CD4+ gp 120+ cells in the blood, the lower the T cell response in vitro (P = 0.001). Moreover, an association was found between immune complex-positive cells and plasma neopterin (P = 0.01). Patients with increased plasma neopterin levels had decreased in vitro responses to pokeweed mitogen (PWM) (P = 0.006), phytohaemagglutinin (PHA) (P = 0.004), concanavalin A (Con A) (P = 0.09), and anti-CD3 MoAb (P = 0.03), and decreased CD4+ cell counts in the blood (P = 0.006). Since maximally 1% of CD4+ lymphocytes are infected with HIV, T cell dysfunction and T cell depletion in HIV-infected patients may also be caused by the release of free gp120 that binds to uninfected CD4+ cells. Our data suggest that the functional inhibition and subsequent elimination of uninfected CD4+ lymphocytes with surface gp120-immunoglobulin-complement complexes may be a pathomechanism in the manifestation of AIDS.

Signal requirements for activation of leukaemic T cells from a chronic lymphocytic leukaemia (T-CLL)

In order to define the signal requirements for leukaemic T cell activation, the proliferation and interleukin-2 (IL-2) production of peripheral lymphocytes from a patient with a HTLV-I-, CD4+, CD45RA+ CD45RO+ CD25- T-CLL were evaluated after the delivery of different stimuli. Unlike resting CD4+ normal T lymphocytes that can be activated only by a two-signal stimulation, T-CLL cells proliferated and released IL-2 in response to a pair of anti-CD2 monoclonal antibodies (MoAbs) or concanavalin A (Con A) in the absence of both accessory cells (AC) and phorbol myristate acetate (PMA). The two stimuli were also able to induce CD25 expression within 12-20 h on the majority of T-CLL cells. A response to anti-CD3 and anti-CD28 MoAbs was detected only in the presence of PMA, similar to that observed in normal resting T lymphocytes matched for phenotype. Both Con A- and CD2-induced proliferation were strongly inhibited by the addition of anti-CD25 MoAb. Furthermore, T-CLL lymphocytes acquired anti-tumour lytic activity after culture in the presence of PMA and ionomycin. We conclude that HTLV1- CD25- T-CLL can be characterized not only by morphological and phenotypical studies but also on the basis of signal requirements for cell activation.

Co-stimulation with anti-CD28 (Kolt-2) enhances DNA synthesis by defective T cells in common variable immunodeficiency.

In normal T cells, an anti-CD28 MoAb (Kolt-2) will synergize with the mitogenic stimuli phytohaemagglutinin (PHA), anti-CD3 (OKT3) or a combination of anti-CD2 antibodies (OKT11 and GT2) in the induction of DNA synthesis. A subgroup of patients with common variable immunodeficiency (CVID) show a defect in DNA synthesis by T cells stimulated in vitro with the above mitogens. We have now investigated whether anti-CD28 will correct the defect. This strategy partially restored DNA synthesis, providing evidence that the CD28 co-stimulatory pathway in CVID T cells is normal. Ligation of CD28 acts through co-stimulating IL-2 secretion. The natural ligand (B7) for CD28 on antigen-presenting cells from CVID patients is expressed normally. We conclude that the defect in CVID T cells lies in pathways that lead to transcription of the IL-2 gene other than that induced by ligation of CD28 with Kolt-2.