摘要:

AbstractWe examined the hypothesis that the adult human gastrointestinal tract is a site of extrathymic T cell differentiation. When T lymphocytes undergo gene rearrangement, the products of both RAG1 and RAG2 genes are expressed; RAG mRNA is present only in tissue governing lymphocyte maturation. In this study, reverse transcription polymerase chain reaction (RT‐PCR) was used to detect RAG1‐ and RAG2‐specific mRNA. Total RNA was purified from small intestinal samples from five adults. Peripheral blood mRNA from the same patient was used as a negative control in two cases. Bone marrow RNA preparations from two healthy donors were used as positive controls. cDNA synthesis was carried out using random hexamers. Primers for first round and nested PCR of RAG1 and RAG2 were synthesized. RAG1 and RAG2 mRNA was detected in all bone marrow preparations but was absent in all peripheral blood samples. RAG1 and RAG2 mRNA was detected in the small intestine of four of the five patients studied. RAG1 and RAG2 expression was localized in the epithelial layer and absent in the lamina propria. RAG1 and RAG2 expression in the epithelial layer is strong evidence that T cell differentiation occurs in the adult human inte

ISSN:0014-2980    

DOI:10.1002/eji.1830250502

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe superantigen staphylococcal enterotoxin B (SEB) induces a defect in interleukin (IL)‐2 production by T cells expressing specific T cell receptor Vβ domains. The present study was undertaken to determine the capacity of T cells, made deficient in IL‐2 production by exposure to SEBin vivo, to secrete interferon (IFN)‐γ and IL‐10 and to induce pathology upon SEB rechallenge. For this purpose, BALB/c mice received two intraperitoneal injections of 100 μg SEB with a 48‐h interval. First, we compared peak serum levels of IL‐2, IFN‐γ and IL‐10 after SEB rechallenge with those measured after a single SEB injection in control mice. The expected defect in IL‐2 production in SEB‐pretreated mice was associated with a major increase in IL‐10 and IFN‐γ levels which were about fivefold higher than in controls. Experiments in mice depleted of CD4+or CD8+cells as well as studies in which purified T cell populations were rechallenged with SEBin vitroindicated that both CD4+and CD8+cells from SEB‐pretreated mice were primed for IL‐10 and IFN‐γ production. Furthermore, SEB‐pretreated mice were sensitized to the toxic effects of the superantigen as indicated by a 30‐70% lethality rate (vs. 0% in naive mice) within 48 h after SEB rechallenge. IFN‐γ was involved in the lethal syndrome as it could be prevented by injection of neutralizing anti‐IFN‐γ monoclonal antibody. We conclude that SEB‐reactive T cells made deficient for the production of IL‐2 by exposure to SEBin vivoare primed for IFN‐γ and IL‐10 production, and that IFN‐γ up‐regulation is

ISSN:0014-2980    

DOI:10.1002/eji.1830250503

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractAlthough the transfection of B7‐1 cDNA into a few mouse tumor cell lines can induce anti‐tumor T cell immunity, its expression alone is ineffective in many other tumor cell lines tested. We were interested to study what factors limit B7‐1 co‐stimulatory activity, and decided to investigate whether B7‐1 requires the cooperation of ICAM‐1 to provide the minimal co‐stimulatory signal for establishing an efficient anti‐tumor immunity. We show that the transfection of B7‐1 cDNA into three ICAM‐1+(plasmocytoma J558L, T lymphomas EL‐4 and RMA), but not into two ICAM‐1−tumor cell lines (adenocarcinoma TS/A and melanoma B16.F1), is sufficient to induce their complete rejection in syngeneic mice. The expression of ICAM‐1 is necessary for the rejection of the B7 expressing tumors, since the primary response elicited by B7‐1+EL‐4 and RMA clones expressing reduced levels of ICAM‐1 is severely reduced. Furthermore, super‐transfection of ICAM‐1 cDNA into B7‐1+adenocarcinoma and melanoma clones optimizes their primary rejection. Histologic examination of transfected tumors reveals that B7‐1 and ICAM‐1 exert a potent pro‐inflammatory activity. The intra‐tumor infiltration is composed of both eosinophils and lymphomono‐cytes, and is already massive 5 days after the tumor challenge. The primary rejection of the B7‐1+ICAM‐1+tumors depends critically on CD8+T cells, natural killer cells and granulocytes, but is independent of CD4+T cells. Remarkably, in addition to its effects on the early phases of the immune response, the co‐expression of ICAM‐1 and B7‐1 on tumors is also necessary for the efficient induction of a memory response. In fact, only the primary challenge with B7‐1+, ICAM‐1+tumor cells protects the majority of the mice from a second injection of parental tumor cells. Collectively, our findings indicate that B7‐1 and ICAM‐1 are fundamental components for triggering the primary rejection of tumors and establishing a protective memory response. These findings may help to define new strategies fo

ISSN:0014-2980    

DOI:10.1002/eji.1830250504

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractHeat‐stable antigen (HSA/J11d/possibly homologous to CD24), a cell adhesion molecule capable of providing a co‐stimulatory signal for T cell proliferation, is expressed on B cells, activated T cells, monocytes, granulocytes, Langerhans cells and thymocytes. Recent studies have demonstrated that co‐stimulatory signals provided by cell adhesion molecules such as B7‐1 play an essential role in generation of an anti‐tumor immune response. To examine whether the co‐stimulatory signal provided by HSA can induce an anti‐tumor immune response, we have transfected HSA cDNA into the murine melanoma cell line K1735M2, and examined the ability of this transfected cell line to induce tumor‐specific T cell responses. The results demonstrate that spleen cells from mice immunized with HSA‐transfected K1735M2 cells showed enhanced T cell proliferation in a mixed lymphocyte tumor reaction (MLTR) assay and also demonstrated a significant anti‐tumor cytotoxicity to the parent tumor cell (K1735M2). This anti‐tumor cytolytic activity could be abrogated by pretreatment of effector cells with anti‐mouse CD8 monoclonal antibody and complement. Under similar conditions, spleen cells from C3H mice immunized with vector‐transfected K1735M2 cells neither actively proliferate in an MLTR assay, nor did they exert significant cytolytic activity against the respective tumor cells. In summary, our study demonstrated that HSA can provide a co‐stimulatory signal for the T cell immune response against tu

ISSN:0014-2980    

DOI:10.1002/eji.1830250505

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe diversity of cytokine production patterns displayed by T cells activatedin vivowas investigated by analyzing short‐term antigen‐specific CD4+T cell clones and single CD4+T cells derived from draining lymph nodes of mice undergoing a T helper 2 (Th2)‐like response to keyhole limpet hemocyanin (KLH). On average, 2.7% of CD4+lymph node cells gave rise to clones in the presence of the immunizing antigen and, of these, about 90% secreted interleukin‐4 (IL‐4) and 20% secreted interferon‐γ (IFN‐γ) when restimulated after 2 weeksin vitro. Almost all IFN‐γ‐producing clones co‐produced IL‐4. The definition of clones as positive or negative for cytokine synthesis depended on assay sensitivity, however, since their titers were distributed continuously from the threshold of detection over at least a 1000‐fold range.Reverse‐transcription polymerase chain reaction analysis of 59 clones revealed multiple patterns of co‐expression of IL‐2, IL‐3, IL‐4, IL‐6, IFN‐γ and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) mRNA. Although most clones contained detectable IL‐4 and IL‐6 mRNA and a minority contained IFN‐γ mRNA, only 1 clone expressed the canonical Th2 cytokine profile. The observed frequencies of mRNA co‐expression for most of the six cytokines (including IL‐4 with IFN‐γ), and the frequency of co‐secretion of IL‐4 and IFN‐γ, were not significantly different from those predicted for random association. Independent regulation of IL‐4 and IFN‐γ mRNA expression was confirmed at the single‐cell level in a polyclonal population of KLH‐primed CD4+cells, among which co‐expression of these cytokines again occurred at the frequency predicted for a random event. The data suggest that the polarization of this immune response towards a Th2 cytokine profile is achieved by altering the probabilities of expression of the IL‐4, IFN‐γ and other cytokine genes at

ISSN:0014-2980    

DOI:10.1002/eji.1830250506

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractExperimental autoimmune encephalomyelitis (EAE) is an inflammatory disease of the central nervous system (CNS) which can be induced, in susceptible strains like Lewis rats, by transfer of activated myelin basic protein (MBP)‐specific CD4+T lymphocytes. The role of cerebral endothelium in the onset of EAE, with regard to adhesion, activation and infiltration in the CNS of encephalitogenic T lymphocytes, is not fully understood. When pretreated by interferon‐γ, the immortalized Lewis rat brain microvessel endothelial (RBE4) cells expressed major histocompatibility complex class II molecules and stimulated MBP‐specific proliferation and cytolytic activity of the syngeneic encephalitogenic T cell line, designated PAS. However, RBE4‐stimulated PAS lymphocytes subsequently entered an unresponsive state, known as anergy. When inoculated in syngeneic animals, anergic PAS cells, although still cytotoxic, failed to induce EAE, and no cell infiltration was detectable within CNS. The addition of interleukin‐1β (IL‐1β) during MBP presentation by RBE4 cells prevented T cell anergy induction, and maintained T cell encephalitogenicity, although PAS cells stimulated in these conditions caused delayed and attenuated clinical signs of EAE, with only discrete inflammatory lesions in the CNS, compared with EAE induced by PAS cells fully activated by thymic cells. Altogether, our results indicate that MBP presentation by brain microvessel endothelial cells to encephalitogenic T cells induces T cell anergy and loss of pathogenicity. In addition, IL‐1β co‐stimulation of T cells prevents anergy inductionin vitroand at least partially maintains encepha

ISSN:0014-2980    

DOI:10.1002/eji.1830250507

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractInterferon‐γ (IFN‐γ) exerts both enhancing and suppressing influences on collagen‐induced arthritis (CIA), depending on the route and protocol of administration. To study the role of IFN‐γ on the autoimmune process of CIA, we treated DBA/1 mice with two different rat monoclonal antibodies (mAb) to murine IFN‐γ. Treatments, given twice weekly for 4 weeks, consisted of intraperitoneal injections of either mAb. In early treatments, starting from the day of immunization with type II collagen (CII), the severity of arthritis was reduced in both groups of anti‐IFN‐γ‐treated mice compared with control groups. Moreover, anti‐CII antibody levels decreased in the sera of these mice. CIA was also down‐regulated in mice treated from days 14 or 28 post immunization. In contrast, late treatments with anti‐IFN‐γ mAb either induced aggravating effects, or did not affect the course of the disease. On the other hand, administration of high doses (8 × 104U three times/week) of rat recombinant IFN‐γ exerted a transient increase of CIA severity. These findings suggest that IFN‐γ may play a critical role during both the induction and the course of CIA, first enhancing the immune response, and t

ISSN:0014-2980    

DOI:10.1002/eji.1830250508

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractTo understand the role of CD8+T cells in experimental autoimmune myasthenia gravis (EAMG), CD8+T cells were depleted by injecting a monoclonal anti‐rat CD8 antibody (OX8) into Lewis rats immunized withTorpedoacetylcholine receptor (AChR) in complete Freund's adjuvant (CFA). CD8‐depleted EAMG rats showed strikingly less muscle weakness and lower anti‐AChR IgG antibody levels compared to Hy2‐15‐injected control EAMG rats. Moreover, the numbers of AChR‐specific IgG antibody‐secreting cells, AChR‐reactive interferony‐γ‐secreting T helper type 1‐like cells and lymphocyte proliferation to AChR were lower in the CD8‐depleted group than in control EAMG rats. These differences were significant among mononuclear cells from inguinal and popliteal lymph nodes, mesenteric lymph nodes and spleen, but not from thymus when examined 3, 5 and 7 weeks post‐immunization. We suggest that CD8+T cells are involved in the induction and persistance of EAMG by directly or indirectly affecting AChR‐reactive T cells and anti‐ACh

ISSN:0014-2980    

DOI:10.1002/eji.1830250509

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractLymphocytes continuously migrate through the body, and their efficient extravasation from the bloodviahigh endothelial venules (HEV) is essential for initiating an appropriate immune response. Most investigations have focused on the lymphocyte/HEV interactionin vitro. However, to what extent such systems reflect the situationin vivois not known. It is also unclear whether lymphocyte subsets immigrate into the HEV in proportion to their presence in the blood, and whether import capacity is limited by the HEV. When rat mesenteric lymph node lymphocytes were incubatedin vitroon cryostat sections, the well‐known preferential binding of B lymphocytes to HEV of Peyer's patches (PP) and T cells to HEV of axillary lymph nodes (axLN) was observed (axLNvs. PP: B lymphocytes 21.2 ± 5.0%vs. 40.6 ± 11.0%, T lymphocytes 84.6 ± 6.3%vs. 56.5 ± 12.9%). However, when labeled mesenteric lymph node lymphocytes were injected and their location within the HEV was analyzed 15 min later, no preferential interaction was seen. After injection of labeled thoracic duct lymphocytes, the percentage of labeled cells among B and T lymphocytes in the blood was significantly different (4.4 ± 0.9%vs. 8.9 ± 3.6%), whereas that in HEV of axLN (19.0 ± 6.4%vs. 16.6 ± 6.0%) and PP (30.6 ± 6.1%vs. 33.9 ± 4.4%) was comparable. Although the number of injected lymphocytes was similar in magnitude to the total blood lymphocyte pool, after injection there was no increase in lymphocyte numbers in the HEV. Thus, the adhesion assayin vitrodoes not completely reflect immigration into HEVin vivo. In addition, our data suggest that both the availability of lymphocyte subsets in small venules and the immigration rate into HEV are actively regul

ISSN:0014-2980    

DOI:10.1002/eji.1830250510

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe conditions required for sensitizing naive T cells to nominal antigen are poorly understood. In this report we describe anin vitrosystem for generating antigen‐specific CD4+T cells from previously unprimed individuals. Freshly isolated CD4+T cells were cultured with keyhole limpet hemocyanin (KLH), sperm whale myoglobin (SWM), or human immunodeficiency virus (HIV) gp 160, antigens to which most persons have not been sensitized, in the presence of either dendritic cells (DC) or macrophages (MΦ). In short‐term (<8 days) cultures, CD4+T cells or their CD4+, CD45RA (naive) subpopulation mounted significant proliferative responses to KLH, SWM, and HIV gp160, but only if the antigens were presented by DC. In contrast, CD4+, CD45RO (memory) T cells responded poorly to these antigens, although they responded vigorously to tetanus toxoid, a recall antigen, presented by either DC or MΦ. KLH‐ and SWM‐specific CD4+T cell lines were established from the starting population that had been sensitizedin vitro, following repeated stimulation with antigen and MΦ in medium supplemented with interleukin‐2 and interleukin‐4. Despite the continued presence of these cytokines during T cell expansion, the expanded lines retained their ability to respond to the priming antigen in the absence of exogenous cytokines. When the CD45RA and CD45RO subpopulations were sensitized and expanded separately, the CD45RA cells alone gave rise to antigen‐specific T cell lines, while the CD45RO cells proliferated nonspecifically. These results demonstrate that human naive CD4+T cells can be sensitizedin vitroto nominal antigens presented by DC and that the sensitized cells can be expanded into long‐term lines that retain their a

ISSN:0014-2980    

DOI:10.1002/eji.1830250511

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY