Biomedical subjects

H Offner

Publications and source records attributed to H Offner.

At least 37 records · Page 2Linked to original sources

PubMed1996

MHC-restriction, cytokine profile, and immunoregulatory effects of human T cells specific for TCR V beta CDR2 peptides: comparison with myelin basic protein-specific T cells.

HLA-DR2+ patients with multiple sclerosis (MS) that respond to vaccination with TCR V beta 5.2-38-58 peptides have increased frequencies of TCR peptide-specific T cells, reduced frequencies of myelin basic protein (MBP)-specific T cells, and a better clinical course than non-responders. To evaluate possible network regulation of MBP responses by TCR peptide-specific T cells, we compared properties of both cell types. Both MBP- and TCR peptide-specific T cell clones were CD4+ and predominantly HLA-DR restricted. HLA-DR2, which is in linkage disequilibrium in MS patients, preferentially restricted TCR peptide-specific clones as well as MBP-specific responses in HLA-DR2 and DR2,3+ donors. Within the DR2 haplotype, however, both DR beta 1*1501 and DR beta 5*0101 alleles could restrict T cell responses to V beta CDR2 peptides, whereas responses to MBP were restricted only by DR beta 5*0101. TCR peptide-specific clones expressed message for Th2 cytokines, including IL-4, IL-5, IL-6, IL-10, and TGF-beta, whereas MBP-specific T cell clones expressed the Th1 cytokines IFN-gamma and IL-2. Consistent with the Th2-like cytokine profile, TCR peptide-specific T cell clones expressed higher levels of CD30 than MBP-specific T cells. Culture supernatants from TCR peptide-specific T cell clones, but not from MBP- or Herpes simplex virus-specific T cells, inhibited both proliferation responses and cytokine message production of MBP-specific T cells. These results demonstrate distinct properties of MBP and TCR peptide-specific T cells, and indicate that both target and bystander Th1 cells can be inhibited by Th2 cytokines secreted by activated TCR peptide-specific T cells. These data support the rationale for TCR peptide vaccination to regulate pathogenic responses mediated by oligoclonal T cells in human autoimmune diseases.

Adult↗

PubMed1996

Prevention and treatment of relapsing autoimmune encephalomyelitis with myelin peptide-coupled splenocytes.

Injection of antigen cross-linked accessory cells has proven to be an efficient and highly selective approach for inducing epitope-specific peripheral tolerance. This approach has been used successfully to inhibit induction of experimental autoimmune encephalomyelitis (EAE) and to dissect the relative dominance of component encephalitogenic determinants that contribute to both acute and relapsing EAE. In this study, we evaluated the tolerogenic effect of the dominant encephalitogenic epitope for SJL/J mice, residues 139-151 of myelin proteolipid protein (PLP), on the induction and relapses of EAE induced actively with PLP139-151/CFA. Our results demonstrate the powerful protective effect of treating mice before induction of EASE with PLP139-151-conjugated splenocytes (SPL) on the incidence and severity of both the initial episode and the first relapse of EAE. Moreover, treatment of mice on the first day of onset of clinical signs of EAE reduced the severity of the first relapse, apparently by reducing T cell recognition of PLP139-151, although no significant therapeutic effect was observed during the initial treated clinical episode. These data demonstrate the utility of using neuroantigen-coupled accessory cells to prevent and treat relapsing EAE.

Amino Acid Sequence↗

PubMed1996

Neonatal injection of Lewis rats with recombinant V beta 8.2 induces T cell but not B cell tolerance and increased severity of experimental autoimmune encephalomyelitis.

In Lewis rats with experimental autoimmune encephalomyelitis (EAE) mediated by V beta 8.2 effector cells, anti-idiotypic T cells and antibodies could be boosted by injection of V beta 8.2 peptides, inducing both T cells and antibodies that reduced the severity and shortened the course of disease. However, EAE in Lewis rats is self-limiting, and we sought to determine if the anti-idiotypic response contributed to the natural recovery process. In a previous study, we found that adult tolerance induced to one of the regulatory idiotopes, V beta 8.2-44-54, caused worsening of EAE, implicating response to this epitope in recovery from EAE. However, neonatally-induced tolerance to V beta 8.2-44-54 did not alter the course of EAE, suggesting either compensation by additional V beta 8.2 determinants, or mechanistic differences in tolerization protocols. In this report, we reevaluate the role of V beta 8.2 determinants in recovery from EAE, using two recombinant V beta 8.2 constructs to induce neonatal tolerance to the comprehensive set of V beta 8.2 epitopes prior to adult induction of EAE. We found that neonatal exposure to either of the recombinant V beta 8.2 molecules induced "split" tolerance-specific T cell tolerance but enhanced antibody responses- and a more severe course of EAE. In contrast, neonatal exposure to a V beta 8.2 + T cell hybridoma or a control protein did not induce T cell tolerance to V beta 8.2 determinants and did not alter the EAE disease course. These results are consistent with those obtained by inducing adult tolerance, and suggest that our previous result (normal recovery from EAE in rats neonatally tolerized to V beta 8.2-44-54) was probably due to a compensatory response to other V beta 8.2 determinants. In both studies, the data clearly implicate T cell recognition of V beta 8.2 determinants in the natural EAE recovery process.

Amino Acid Sequence↗

PubMed1996

Treatment of relapsing autoimmune encephalomyelitis with T cell receptor V beta-specific antibodies when proteolipid protein is the autoantigen.

Monoclonal antibodies (mAbs) directed against the V beta chain of the T cell receptor (TCR) of pathogenic T cells have been used to treat acute murine experimental autoimmune encephalomyelitis (EAE) induced by myelin basic protein (BP). We evaluated anti-V beta mAb for the treatment of relapsing EAE (R-EAE) induced in SJL/J mice by the myelin proteolipid protein (PLP) peptide 139-151. Spinal cord mononuclear cells isolated from mice immunized for R-EAE with PLP 139-151 were shown to express a predominance of V beta 2 and V beta 17 during acute and relapsing disease. T cell lines specific for PLP 139-151 were magnetically sorted to express 80-90% V beta 2. These V beta 2-enriched lines induced typical relapsing demyelinating EAE in naive recipient mice. SJL/J mice with R-EAE induced by a PLP 139-151-specific T cell line expressing 88% V beta 2 were treated with anti-V beta 2 mAb. Anti-V beta 2 mAb markedly reduced clinical and histological disease severity when given at the time of cell transfer or when given at clinical disease onset. In contrast, anti-V beta mAbs showed only a mild clinical effect on R-EAE induced by immunization with PLP 139-151 or R-EAE transferred by a PLP 139-151-specific T cell line expressing multiple V beta s. A cocktail of mAbs directed against V beta 2, V beta 4, and V beta 17 significantly reduced the numbers of spinal cord T cells expressing these V beta s during acute EAE but had little effect on disease course, suggesting that pathogenic T cells expressing other V beta s were producing disease. These findings may have implications for the treatment of multiple sclerosis with V beta-selective therapy.

Analysis of Variance↗

PubMed1996

Myelin basic protein specific T-helper cells induce experimental anterior uveitis.

Immunopathological changes in the eyes were examined in Lewis rats after active and passive induction of experimental autoimmune encephalomyelitis (EAE) with myelin basic proteins (MBP) at various stages of EAE. The onset of anterior uveitis (AU) coincided with hind limb paralysis, but uveitis persisted after clinical signs of EAE had subsided. A mild form of uveitis was characteristic for the majority of rats. The changes within the iris and ciliary body consisted of an accumulation of inflammatory cells lining the anterior surface of iris, the trabecular meshwork, and, in some cases, within the ciliary body and the aqueous humor. A similar histopathological picture was observed when rats were injected with the secondary encephalitogenic determinant for Lewis rats, MBP peptide 87-99. Flow cytometry analysis of T cells from the anterior segment of the inflamed eyes after immunization with MBP revealed the presence of CD4+ cells exclusively expressing V beta 8.2 and OX-40 markers. Our data suggest that MBP are encephalitogenic and uveitogenic in Lewis rats and that the V beta 8.2-positive T cells in the eye represent encephalitogenic T cells. Many of those T cells were distributed in the iris and the anterior chamber. These findings indicate that these MBP-specific T cells may play a critical role in EAE as well as in AU.

Animals↗

PubMed1996

V beta CDR3 motifs associated with BP recognition are enriched in OX-40+ spinal cord T cells of Lewis rats with EAE.

Spinal cord (SC) T cells were isolated at the onset of actively induced experimental autoimmune encephalomyelitis (EAE) and sorted for the presence of the OX-40 activation marker. Previously, we reported an enhanced bias in V beta 8.2 expression as well as enhanced proliferative responses to basic protein antigens among the OX-40+ SC T cells. Here we demonstrate that CDR3 motifs associated with EAE are present at a significantly higher frequency in V beta 8.2 sequences of OX-40+ SC T cells (16/17) compared with those of OX-40- SC T cells (5/17). Thus, the OX-40 antigen may be useful as a marker to isolate and characterize autoantigen-specific T cells from the site of inflammation in T-cell-mediated autoimmune diseases.

Animals↗

PubMed1996

T cell receptor peptides in treatment of autoimmune disease: rationale and potential.

The natural tendency in T cell-mediated autoimmune conditions to develop focused antigen-specific responses that over-utilize certain T cell receptor (TCR) V region segments prompts the induction of anti-TCR-specific T cells and antibodies that can inhibit the pathogenic T cells and promote recovery from disease. This natural regulatory network can be manipulated by injecting synthetic peptide vaccines that correspond to segments of the over-expressed V genes. In experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis (MS), the pathogenic T cells are directed at myelin components, including basic protein (MBP). In some strains such as the Lewis rat and the PL/J mouse, the encephalitogenic BP-specific T cells overexpress a particular V region gene (V beta 8.2) in the TCR. In vivo administration of V beta 8.2 peptides in rats or mice can prevent and treat EAE by boosting regulatory anti-V beta 8.2-specific T cells that inhibit but do not delete the encephalitogenic specificities. This regulation is mediated by soluble factors, suggesting that the presence of regulatory TCR-specific T cells within the target organ (the central nervous system) may inhibit not only the stimulating V beta 8.2 + T cells, but also bystander T cells bearing different V genes. Parallel studies in MS patients have revealed striking V gene biases among BP-specific T cell clones from some patients that provided a rationale for TCR peptide therapy. Injection of V beta 5.2 and V beta 6.1 peptides boosted the frequency of TCR peptide-specific T cells and reduced responses to BP, in some cases with clinical benefit, indicating the presence of an anti-TCR regulatory network in humans that may also be manipulated with TCR peptide therapy.

Animals↗

PubMed1996

Natural immunodominant and experimental autoimmune encephalomyelitis-protective determinants within the Lewis rat V beta 8.2 sequence include CDR2 and framework 3 idiotopes.

The V beta 8.2-39-59 peptide has served as a prototypic natural regulatory idiotope in Lewis rats developing experimental autoimmune encephalomyelitis (EAE). The purpose of the present study was to determine if additional regulatory regions were contained within the V beta 8.2 sequence expressed by most encephalogenic T cells. A comprehensive strategy utilizing V beta 8+ hybridomas, a recombinant (r) V beta 8.2 molecule, and overlapping synthetic V beta 8.2 peptides reconfirmed the natural recognition of the 39-59 idiotope, and revealed a second immunodominant and EAE-protective determinant residing within residues 71-90. Both the V beta 8.2-39-59 and V beta 8.2-71-90 peptides were immunogenic, and each was recognized after immunization of Lewis rats with V beta 8+ cells or rV beta 8.2, indicating the preservation of these epitopes during the processing of the V beta 8.2 chain. Moreover, both epitopes were recognized naturally by T cells from rats developing or recovering from EAE that had never been purposefully immunized with V beta 8.2 peptides or rV beta 8.2. Of additional interest, the V beta 8.2-31-50 peptide was recognized by T cells from some rats immunized with complete Freund's adjuvant (CFA) alone. This peptide possessed mildly protective activity against EAE and thus could account for sporadic reports of CFA interference in EAE.

Amino Acid Sequence↗

PubMed1996

OX-40 antibody enhances for autoantigen specific V beta 8.2+ T cells within the spinal cord of Lewis rats with autoimmune encephalomyelitis.

The V beta 8.2 T cell receptor (TCR) component is the predominant V beta gene product associated with antigen specific CD4+ T cell response to the major encephalitogenic epitope of myelin basic protein (MBP) in Lewis rats. Lewis rats were actively immunized with MBP in complete Freund's adjuvant and the V beta 8.2 positive and negative cells were analyzed for IFN-gamma mRNA production and OX-40 cell surface expression during the onset of EAE. The V beta 8.2+ T cells isolated from the spinal cord produced the majority of mRNA for IFN-gamma and also showed a marked enhancement for OX-40 expression compared to V beta 8.2+ T cells isolated from the lymph nodes. Only a fraction of IL-2 receptor positive T cells examined ex vivo from the inflammatory compartments co-expressed the OX-40 antigen. These results suggested that OX-40 cell surface expression could be used to identify and isolate the most recently activated T cells ex vivo. OX-40+ T cells isolated from the spinal cord were highly enriched for the V beta 8.2 T cell receptor component compared to OX-40- or unsorted spinal cord lymphocytes. OX-40+ T cells isolated from the spinal cord had an enhanced response to MBP, whereas OX-40+ cells isolated from the lymph nodes responded to both MBP and purified protein derivative. These data suggest that activated T cells can be isolated and characterized with the OX-40 antibody which only respond to the antigens present at the local site. The data also imply that isolation of OX-40+ T cells will be useful in identifying V beta biases and autoantigen specific cells within inflamed tissues even when the antigen specificity is unknown.

Animals↗

PubMed1996

Prior exposure to superantigen can inhibit or exacerbate autoimmune encephalomyelitis: T-cell repertoire engaged by the autoantigen determines clinical outcome.

Experimental allergic encephalomyelitis (EAE) is inducible in experimental animals immunized with myelin basic protein (MBP), proteolipid protein (PLP) or their peptides. We compared T-cell responses to encephalitogenic epitopes of PLP(43-64) and MBP(Ac1-11) in a single mouse strain, (PL/J x SJL)F1. MBP(1-11)-specific T-cell hybridomas expressed predominantly TCR V beta 8 or V beta 4, while PLP(43-64)-specific hybridomas expressed a diverse TCR repertoire. To analyze the biologic significance of the TCR repertoire (limited vs. diverse) to disease susceptibility, we pretreated mice with a superantigen (SEB), and then induced disease with these autoantigens. Mice injected with SEB and immunized with MBP(Ac1-11) showed significant inhibition of EAE, whereas SEB-pretreated mice immunized with PLP(43-64) had an increased severity of EAE and developed a chronic disease. These data demonstrate that prior exposure to microbial superantigens can significantly alter the autoimmune disease course depending upon the TCR repertoire used by the autoantigen.

Animals↗

PubMed1996

Selective depletion of myelin-reactive T cells with the anti-OX-40 antibody ameliorates autoimmune encephalomyelitis.

The OX-40 protein was selectively upregulated on encephalitogenic myelin basic protein (MBP)-specific T cells at the site of inflammation during the onset of experimental autoimmune encephalomyelitis (EAE). An OX-40 immunotoxin was used to target and eliminate MBP-specific T cells within the central nervous system without affecting peripheral T cells. When injected in vivo, the OX-40 immunotoxin bound exclusively to myelin-reactive T cells isolated from the CNS, which resulted in amelioration of EAE. Expression of the human OX-40 antigen was also found in peripheral blood of patients with acute graft-versus-host disease and the synovia of patients with rheumatoid arthritis during active disease. The unique expression of the OX-40 molecule may provide a novel therapeutic strategy for eliminating autoreactive CD4+T cells that does not require prior knowledge of the pathogenic autoantigen.

Animals↗

PubMed1996

Treatment of multiple sclerosis with T-cell receptor peptides: results of a double-blind pilot trial.

A T-cell receptor (TCR) peptide vaccine from the V beta 5.2 sequence expressed in multiple sclerosis (MS) plaques and on myelin basic protein (MBP)-specific T cells boosted peptide-reactive T cells in patients with progressive MS. Vaccine responders had a reduced MBP response and remained clinically stable without side effects during one year of therapy, whereas nonresponders had an increased MBP response and progressed clinically. Peptide-specific T helper 2 cells directly inhibited MBP-specific T helper 1 cells in vitro through the release of interleukin-10, implicating a bystander suppression mechanism that holds promise for treatment of MS and other autoimmune diseases.

Adult↗

PubMed1995

Myelin antigen-coupled splenocytes suppress experimental autoimmune encephalomyelitis in Lewis rats through a partially reversible anergy mechanism.

Mechanisms of adult tolerance induced by injecting myelin Ag/ECDI (ethyl carbodiimide)-coupled splenocytes (Ag-SPL) were evaluated in Lewis rat experimental autoimmune encephalomyelitis (EAE). Rats could be tolerized against the major encephalitogenic epitope of guinea pig basic protein (Gp-BP), residues 72-89, using either S72-89-SPL or crude spinal cord homogenate (SCH)-SPL. In contrast to lymph node responses that were not affected significantly, the proliferation responses of blood T cells were markedly inhibited at the peak of EAE and during the recovery period to both Gp-BP and S72-89, but not to purified protein derivative (PPD), demonstrating Ag-specific tolerance. Tolerance induction reduced the number of infiltrating spinal cord (SC) cells, especially recruited CD45RC+ cells, as well as SC proliferation responses to S72-89 throughout the course of EAE. In contrast, SC response to PPD was increased at onset of EAE, but later during recovery the PPD response was also decreased compared with control rats. Tolerance induced by S72-89-SPL in blood and SC T cells could be reversed by incubation in IL-2, in accordance with an anergy model. BP-specific T cells preincubated in vitro with Gp-BP-SPL were rendered unresponsive to Gp-BP or S72-89, compared with the same T cells preincubated with histone (Hist)-SPL that remained Ag responsive. Consistent with an anergy model, preincubation with BP-SPL+IL-2 partially prevented tolerance induction to BP. T cells tolerized in vitro to BP-SPL induced milder EAE with delayed onset compared with control-tolerized T cells that produced lethal disease. These results demonstrate the efficacy of myelin Ag-coupled SPL in preventing EAE by selective tolerization of encephalitogenic T cells through a partially reversible anergy-induction mechanism.

Amino Acid Sequence↗

PubMed1995

Analysis of V beta 8.2 CDR3 sequences from spinal cord T cells of Lewis rats vaccinated or treated with TCR V beta 8.2-39-59 peptide.

Experimental autoimmune encephalomyelitis (EAE) in the Lewis rat can be induced with the administration of Gp-BP. This disease appears to be mediated at least in part by V beta 8.2+CD4+T cells, which specifically recognize the BP72-89 encephalitogenic peptide. Treatment or protection with V beta 8.2 CDR2 39-59 peptide can suppress or prevent clinical signs of EAE, presumably through the activation of regulatory T cells. Interestingly, V beta 8.2+ T cells continue to persist in the spinal cord of protected animals, although their appearance in the central nervous system (CNS) is delayed when compared with control animals with EAE. As part of our effort to elucidate the mechanism(s) of peptide protection and therapy, we sought to determine whether the V beta 8.2+ T cells in the spinal cord of protected or treated rats were truly representative of those found in rats with clinical EAE. Therefore, we examined the following CNS samples for the Asp96Ser97 motif, which has been identified previously in V beta 8.2+ BP-specific, encephalitogenic T cell clones: 1) rats protected with V beta 8.2-39-59 peptide, 2) rats treated with V beta 8.2-39-59 peptide, and 3) control rats with EAE. Our findings indicate that EAE-associated V beta 8.2+ sequences can still be found in both peptide-treated and peptide-protected rats. It appears that administration of V beta 8.2 CDR2 peptide does not prevent EAE-associated V beta 8.2+ T cells from infiltrating the CNS and that other mechanisms are at work to prevent the development of EAE.

Amino Acid Sequence↗

PubMed1995

Increased severity of experimental autoimmune encephalomyelitis in rats tolerized as adults but not neonatally to a protective TCR V beta 8 CDR2 idiotope.

The ability of synthetic V region peptides to induce regulatory T cells and Abs in rodents and humans provides clear evidence that these idiotopes do not naturally induce tolerance. In this study, we investigated the ability of TCR V beta 8.2 peptides to experimentally induce specific T cell tolerance, as measured by loss of Ag-specific proliferation and delayed-type hypersensitivity responses, and by increased susceptibility to experimental autoimmune encephalomyelitis (EAE). We found that both neonatal and adult exposure to V beta 8.2-39-59 or V beta 8-44-54 peptides could induce efficient T cell tolerance, resulting in a significant inhibition of peptide-specific proliferative responses. In addition, neonatal tolerance resulted in a partial reduction in delayed-type hypersensitivity response and an inability to vaccinate against EAE after adult immunization with the tolerizing peptide. We further evaluated the contribution of naturally induced TCR-specific responses to EAE resistance induced by challenging neonatally or adult tolerized rats with myelin basic protein in adjuvant. The clinical course of EAE was not significantly altered in rats tolerized neonatally to V beta 8.2 peptides, but both the severity and incidence of mortality from EAE was increased in rats tolerized as adults with V beta 8.2 peptides conjugated to syngeneic splenocytes. These results demonstrate that V beta 8.2 peptides are tolerogenic as well as immunogenic. Moreover, the observation of different effects of neonatal vs adult tolerization on the course of EAE suggests either the emergence of additional protective idiotopes after neonatal tolerization and/or mechanistic differences in the two tolerance-inducing protocols. Most importantly, the enhancement of clinical EAE in rats tolerized as adults with V beta 8.2 peptides provides evidence for an innate regulatory role of the CDR2 idiotope in recovery from EAE.

Aging↗

PubMed1995

Effects of anti-CD4 antibody: enhancement of lymph node PPD-memory T cell response.

In vitro incubations of CD4+ T cells with anti-CD4 monoclonal antibody (Mab) demonstrated saturation binding and inhibited both PPD-stimulated proliferation and delayed-type hypersensitivity (DTH) after passive transfer of these cells into naive rats. In comparison, in vivo administration of anti-CD4 Mab into rats, 2 weeks after CFA immunization (PPD priming), saturated CD4 molecules expressed on T lymphocytes and depleted significant percentages of CD4+ T cells from blood, spleen, and lymph nodes, yet failed to cause significant inhibition of PPD-stimulated DTH ear swelling. Only repeated in vivo administration of anti-CD4 Mabs during the CFA/PPD antigen priming caused significant decreases (36 +/- 5%) in PPD-stimulated DTH ear swelling. T cells isolated from the blood and spleen showed insignificant relative decreases in PPD-stimulated proliferation after anti-CD4 treatments. In contrast, PPD-stimulated proliferation of T cells isolated from the draining lymph nodes after anti-CD4 treatments showed dramatic increases in PPD reactivity. PPD stimulation of T cells isolated from the draining lymph nodes of anti-CD4 Mab-treated rats produced relative phenotypic changes in CD4 coexpressions with CD45RC (inverse memory), CD49d (inflammatory adhesion integrin VLA-4), and OX40 (CD4+ blast), representative of memory CD4+ T cell blasts with reduced capacity for endothelial infiltration. These data demonstrate that depletion of CD4+ T cells by anti-CD4 Mab injections, administered either during or after antigen priming, selectively enhanced memory responses in T lymphocytes in the draining lymph nodes.

Animals↗

PubMed1995

T cells with encephalitogenic potential from multiple sclerosis patients and Lewis rats fail to induce disease in SCID mice following intracisternal injection.

Intracisternal (IC) transfer of cerebrospinal fluid (CSF) mononuclear cells from multiple sclerosis (MS) patients has been reported by others to induce an 'MS-like pathology' in severe combined immunodeficient (SCID) mice. We injected cells from several sources intracisternally into SCID mice and assessed the recipients for clinical and histological disease. CSF cells and myelin basic protein (BP)-specific T lymphocytes from MS patients failed to induce clinical or histological disease following IC injection in SCID mice. Similarly, encephalitogenic BP-specific T cells from Lewis rats were unable to induce disease after IC injection in either SCID mice or Lewis rats, even at cell numbers which induced experimental autoimmune encephalomyelitis in Lewis rats following intraperitoneal (IP) injection. In contrast, naive Lewis rat splenocytes, which were capable of inducing lethal graft-versus-host (GVH) disease following IP transfer in SCID mice, induced paralysis and histopathological changes following IC transfer in SCID mice. We conclude that MS CSF cells do not typically transfer disease into SCID mice following IC injection. Furthermore, it appears likely that neuropathological disease following IC transfer of cells reflects the potential of the transferred cells for inducing GVH disease. Specific recognition of neuroantigens by T cells, as occurs in EAE, is probably not involved in the transfer of paralytic disease by IC transferred MS patient CSF cells.

Animals↗

PubMed1995

Antigen-specific T-cell activations distinguished by in vivo anti-CD4 antibody treatment.

This study identifies activation characteristics of PPD-responsive T-cells that emerge after treatment with anti-CD4 monoclonal antibody (Mab). PPD-stimulated T-cell proliferations, OX40 phenotype and protein tyrosine phosphorylations involving p56lck (pp56lck) were compared to Con A stimulations using T-cells isolated from spleen and draining lymph node of CFA/PPD-immunized rats either untreated or treated in vivo with anti-CD4 Mab. Splenocytes stimulated by concanavalin A (Con A) showed correlated increases in proliferation, levels of pp56lck, and OX40 expression; these parameters were not correlated in splenocytes after PPD-stimulations. T-cells isolated from lymph nodes draining the site of CFA/PPD immunization proliferated in response to stimulation by either PPD or Con A, but only PPD-responsive cells showed correlation to the OX40 activation phenotype and increased levels of pp56lck. CD4+ T-cells isolated from either tissue compartment after anti-CD4 Mab treatments showed higher background and PPD-stimulated proliferations, and expressed lower levels of OX40. In contrast, anti-CD4 Mab treatments reduced (60%) and abolished Con A-stimulated proliferations of splenocytes and lymph node T-cells, respectively. The effects of anti-CD4 Mab treatment on pp56lck levels correlated only to the changes observed for Con A stimulations of splenocytes. These results demonstrate that PPD antigen-specific T-cell populations recovered from different tissue compartments were resistant to in vivo anti-CD4 Mab treatments and did not show the activation changes characteristics of CD4+ T-cells after Con A stimulation.

Animals↗