摘要:

AbstractHuman cluster of differentiation (CD1) is a family of cell surface glycoproteins composed of a 43–49‐kDa heavy chain non‐covalently associated with β2‐microglobulin. Five human CD1 genes have been detected and cloned. Three genes (CD1A, ‐Band ‐C) encode the serologically defined CD1a, ‐b and ‐c antigens. Thus two genes remain,CD1DandCD1E, whose protein products have not been characterized so far. This report describes how a β‐galactosidase‐CD1Dfusion protein was used to raise specific antisera and a monoclonal antibody against theCD1Dgene product. The monoclonal antibody defines a cell surface molecule expressed on a cortical thymocyte cell line and is composed of a 49‐kDa heavy chain associated with β2‐microglobulin, which is serolo

ISSN:0014-2980    

DOI:10.1002/eji.1830210112

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractWe have investigated the requirements for allogeneic stimulation of human CD4 T cells using HLA class II products expressed on various cellular backgrounds. Human (class II‐negative RJ2.2.5 mutant) B cell lines transfected with HLA‐DR or ‐DQ cDNA clones were efficient stimulators for highly purified CD4 T cells. HLA‐DR‐transfected mouse L cells or IFN‐γ‐induced human fibroblasts, although able to function as accessory cells for T cell responses to the mitogen PHA, failed to stimulate strong T cell alloresponses. On the basis of these observations, we have employed class II transfectants to address the following questions: (a) do CD45RA and CD45R0 subpopulations differ in their allogeneic activation requirements, (b) are these subpopulations skewed in their recognition of HLA‐DQvs.HLA‐DR in a manner which might support the concept that CD45RA T cells are involved in HLA‐DQ‐restricted suppressor inducer functions and (c) by using transfectants expressing individual HLA‐DR or ‐DQ heterodimers in combination with limiting dilution analysis, can one for the first time obtain estimates of precursor frequencies for allogeneic cells recognizing each of these class II isotypes? Our results show that CD45RA and CD45R0 T cells respond comparably to optimal numbers of stimulator cells. However, when CD45RA and CD45R0 T cell populations depleted of endogenous accessory cells were cultured with limiting numbers of stimulator cells, CD45R0 cells generally responded more strongly, consistent with the elevated levels of various adhesion molecules known to be expressed by this population. Further, we found a similar representation of responses to HLA‐DR and ‐DQ antigens among populations expressing CD45RA and CD45R0 isoforms. Finally, the precursor frequencies of allogeneic CD4 T cells responding to particular HLA‐DQ alleles were higher than to ‐DQ, but only by a factor of about 1.6, indicating that HLA‐DQ recognition may occur more frequently than implied fro

ISSN:0014-2980    

DOI:10.1002/eji.1830210113

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractLymphocytes infected with the intracellular parasiteTheileria parvaproliferate continuously as lymphoblastoid cell lines. We have previously shown that the continuous proliferation of theT. parva‐infected (Tpi) cell line TpM(803) is mediated in part by an autocrine mechanism (Dobbelaere, D. A. E. et al.,Proc. Natl. Acad. Sci. USA1988.85:4730). We now report that continuous proliferation also requires surface stimulation through cell‐cell contact. Under standard culture conditions this surface stimulus is provided by the infected cells themselves, but it can also be provided by uninfected lymphocytes or macrophages. The ability to respond to surface stimulation is critically dependent on the presence of the parasite in the host cell and is lost within 48 h after the elimination of the parasite from the host cell cytoplasm by treatment with the theilericidal drug BW720c. Tpi cells also secrete a growth factor which is able to support the proliferation of diluted Tpi cells. Growth factor secretion is rapidly lost upon elimination of the parasite. Moreover, inhibition experiments using antiinterleukin 2 (IL 2) antibodies show that IL 2 is involved in the proliferation of the Tpi cell lines TpM(803) and IN10. T cell proliferation is dependent on a number of costimulatory signals which are normally provided by accessory cells. The finding that Tpi cells can mutually stimulate each other to grow in the absence of conventional accessory cells helps to explain how they can escape the normal constraints on T cell growth, allowing them to invade and multiply in non‐lymphoid as well as lymphoid ti

ISSN:0014-2980    

DOI:10.1002/eji.1830210114

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractInterleukin (IL) 4 induces IL 6 production by human umbilical vein endothelial cells (HUVEC) in a dose‐dependent manner, as shown by bioassay and immunoprecipitation. Interferon (IFN)‐γ, which antagonizes IL 4 effects on leukocytes, synergized with IL 4 in the induction of IL 6 production by HUVEC. Contamination with endotoxin was excluded by heat‐inactivated IL 4, preincubating with anti‐IL 4 polyclonal antibody and the use of polymyxin B. The presence of IL 4 receptors on HUVEC was shown by affinity cross‐linking with125I‐IL 4, revealing a 110‐kDa binding protein. However, compared with the amount seen on T cells the 60–70‐kDa cross‐linked doublet was present at much lower levels. Additional lower molecular weight cross‐linked proteins were isolated only with HUVEC, but the origin of these is unclear. IL 6 is a pluripotent cytokine produced by many cells which promotes the differentiation and growth of lymphocytes and the production of acute phase protein by hepatocytes, and is important in the regulation of immunity at the systemic and local levels. Since IL 4 and IFN‐γ are produced by T cells, which are frequently associated with vascular endothelium during chronic inflammation, IL 4 is likely to be an important cytokine in the regulation of IL 6 and perhaps other cytokine product

ISSN:0014-2980    

DOI:10.1002/eji.1830210115

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractWe investigated the capacity of monoclonal antibody (mAb) treatment to prevent graft‐vs.‐host disease (GVHD) in lethally irradiated, allogeneically reconstituted mice, employing anti‐T cell (subset) mAb and a fully allogeneic strain combination. In this strain combination, purified CD4+cells were able to induce a lethal GVH reaction, whereas purified CD8+cells were not. In the same strain combination, a single intraperitoneal injection of IgG2banti‐Thy‐1 mAb, one day after reconstitution, caused a dose‐dependent improvement of the survival. A single injection of a dose as low as 12.5 μg per mouse was already effective. Intravenous and intraperitoneal administration of the mAb appeared equally effective. For effective prevention of GVHD the treatment could be postponed until the 4th day after transplantation, but treatment delayed until day 6 was no longer effective. Treatment with IgG2bmAb specific for either helper or cytotoxic T cells also led to improvement of GVHD and survival, but was less effective than treatment with anti‐Thy‐1 mAb. Clinically, there was a difference in the effectiveness of anti‐CD4 and anti‐CD8 treatment, since symptoms of GVHD started earlier in the anti‐CD8 treated group and the survival was better in the anti‐CD4 treated group. These results press for prospective clinical studies employing anti‐T cell mAb treatment early after allogeneic bone marrow transplantation, especial

ISSN:0014-2980    

DOI:10.1002/eji.1830210116

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractWe have directly followed the formation of and the thymus colonization by pro‐T lymphocytes in the developing C57BL/6 mouse embryo by using the monoclonal antibody JORO 37‐5 specific for pro‐T lymphocytes, immunofluorescence staining and flow fluorocytometry or microscopy analysis. The results show that JORO 37‐5+cells begin to appear in the liver at day 9 of gestation. These JORO 37‐5+cells migrate to and colonize the thymus 1 day later, where they expand vigorously during the next 4–5 days and, subsequently, switch off expression of JORO 37‐5 as they further differentiate into matu

ISSN:0014-2980    

DOI:10.1002/eji.1830210117

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractWe have studied the effects of phorbol‐dibutyrate (PBu2), a protein kinase C (PKC) activator, on the proliferation of peripheral human T cells and thymocyte subpopulations selected by treatment with monoclonal antibodies and complement: pre‐thymocytes (CD1a−CD3−CD4−CD8−), cortical thymocytes (CD3−, class I−antigens) and medullary thymocytes (enriched as CD1a−cells). PBu2induces a dose‐dependent proliferative response in human peripheral blood T cells at concentrations>6 ng/ml, this proliferation being mediated by the autocrine interleukin 2 (IL2)/IL2 receptor (IL2R) pathway. Pre‐thymocytes respond to PBu2in a way similar to T cells, being able to secrete IL2 in significant amounts and express the p55 chain of IL2R. On the other hand, cortical thymocytes are not induced to proliferate after PKC activation and neither expression of the p55 chain of IL2R nor IL2 secretion is observed. Human medullary thymoctes, phenotypically identical to peripheral blood T cells, show no proliferation in response to PBu2at any concentration tested unless IL2 is supplied to the cultures. The activation of PKC induces the expression of IL2R in these cells, but not IL2 secretion. The implications of PKC activation in thymic maturation, the role of IL2 and the relevance of the differences between medullary thymocytes and peripheral blood

ISSN:0014-2980    

DOI:10.1002/eji.1830210118

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractHuman T cells express HLA class II antigens upon activation. Although activated, class II+T cells can present alloantigens under certain circumstances, the functional role of class II antigens on activated T cells remains largely unknown. Here, we report that cross‐linking of HLA‐DR molecules expressed on allospecific, CD4+T clones and cell lines can function as transduction elements that trigger rapid cellular responses including tyrosine phosphorylation of cellular proteins and mobilization of Ca2+from internal stores. The proteins phosphorylated on tyrosine were distinct from those observed after cross‐linking CD4. Ligation of CD4 and class II molecules generated a synergistic effect of the intracellular free Ca2+concentration response that required an interaction between the molecules on the cell surface. Since class II is the natural ligand for CD4, the present data suggest that class II is induced on activated T cells to regulate CD4 function, possibly by specific interaction with the CD4‐associated p56lckprotein tyrosine

ISSN:0014-2980    

DOI:10.1002/eji.1830210119

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractStaphylococcal enterotoxin A (SEA) binds to major histocompatibility complex (MHC) class II molecules on target cells and directs human cytotoxic T lymphocytes (CTL) of irrelevant nominal specificity to mediate strong cytotoxicity against target cells. In this report we describe the importance of ICAM‐1(CD54) expression on the target cell in SEA‐dependent cell‐mediated cytotoxicity (SDCC), utilizing murine L cells co‐transfected with HLA‐DR and ICAM‐1. Human CTL mediated a low but significant cytotoxicity against HLA‐DR2‐and HLA‐DR7‐transfected cells after preincubation with SEA, but no reactivity towards uncoated HLA‐DR2 and HLA‐DR7 cells or SEA‐coated ICAM‐1‐transfected and untransfected L cells. In contrast, a strong cytotoxic response was mediated by CTL against L cells co‐transfected with HLA‐DR/ICAM‐1 and HLA‐DR7/ICAM‐1. Similar cytotoxic activity of the CTL was seen at a 30‐fold lower effector‐to‐target cell ratio when comparing the HLA‐DR2/ICAM‐1‐expressing cells with the HLA‐DR2‐expressing cells. SEA dose‐response analysis demonstrated that the HLA‐DR2/ICAM‐1‐expressing target cells enabled the CTL to respond to a 1000‐fold lower concentration of SEA in comparison to the HLA‐DR2‐expressing cells. CD3+CD4+and CD3+CD8+cytotoxic T cell lines were equally dependent on the expression of ICAM‐1 on the target cell. The strong CTL activity against HLA‐DR2/ICAM‐1‐transfected cells could be blocked by anti‐CD11a or anti‐CD18 monoclonal antibodies (mAb), but not by anti‐CD11b, anti‐CD11c, anti‐CD2 or unrelated control mAb. The great sensitivity of HLA‐DR2/ICAM‐1 expressing target cells to SDCC was strongly reduced by preincubation with various anti‐ICAM‐1 mAb but not by mAb against monomorphic HLA‐DR or murine MHC class I determinants. The result in this study clearly demonstrates that efficient re‐targeting of human CTL by SE is dependent on a proper interac

ISSN:0014-2980    

DOI:10.1002/eji.1830210120

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effect of nerve growth factor (NGF) on human IgG4 production was studied. NGF specifically enhanced IgG4 production in cultures of human tonsillar mononuclear cells without affecting production of other isotypes or other IgG subclasses. Optimal enhancement of IgG4 production by NGF required the presence of T cells. However, NGF induced significant IgG4 production by small resting B cells in the absence of T cells, and this production was enhanced by stimulation withStaphylococcus aureusCowan strain I (SAC). In contrast to small B cells, large activated B cells produced IgG4 spontaneously; this production was enhanced by NGF. NGF also enhanced IgM and IgA production by large B cells, while production of IgG1, IgG2, IgG3 and IgE was not affected. The enhancement of IgG4 production was blocked by anti‐NGF serum but not by control serum. NGF, T cells and SAC, separately or together, failed to induce IgG4 production by surface (sIgG4+)‐depleted B cells. In contrast to NGF, other recombinant human cytokines including interleukin (IL) 1β, IL 2, IL 4, IL 5, IL 6, granulocyte‐macrophage colony‐stimulating factor, interferon α and γ failed to induce IgG4 production. These results suggest that NGF directly and preferentially stimulates activated sIgG4+B cells to pr

ISSN:0014-2980    

DOI:10.1002/eji.1830210121

出版商:WILEY‐VCH Verlag GmbH    

年代:1991

数据来源: WILEY