摘要:

AbstractIn an organ‐cultured murine fetus thymus, precursor cytotoxic T lymphocytes (pCTL) specific for alloantigens developed successfully but those reactive with self antigens were eliminated. In attempting to dissect the mechanism of self tolerance, intrathymic chimera was made by culturing two genetically disparate thymuses in close contact with each other (parabiosis of thymuses). This maneuver resulted in the induction of specific and mutual CTL tolerance. It seems that CTL tolerance was induced by clonal deletion but not by active suppression. Since 2'‐deoxyguanosine treatment abolished the tolerogenic capability of the thymus, hemopoietic cells capable of migrating to and fro in the parabiotic thymuses are thought to be responsible for tolerance induction. Induction of CTL tolerance was dependent on the maturation stages of T cells in the thymus: T cells in 5‐day‐, but not in 7‐day‐cultured thymuses were susceptible to tolerance induction, indicating that T cells expressing T cell receptors at low density are susceptible to toleranc

ISSN:0014-2980    

DOI:10.1002/eji.1830190902

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractCell‐associated and secreted interleukin 1α (IL 1α), IL 1β and tumor necrosis factor α (TNF‐α), produced by human mononuclear cells (MNC)in vitroin response to lipopolysaccharide, were measured by radioimmunoassay. After 18 h of incubation, total production of IL 1α in medium containing 1% heat‐inactivated serum was two‐to‐three times higher than IL 1β. However, in the presence of 1% serum and 5% fresh plasma, IL 1α and IL 1β were produced in similar amounts. Independent of the culture conditions, 90% of the IL 1α remained cell associated whereas 80% of IL 1β was extracellular. The kinetics of production and release of IL 1α, β and TNF‐α were also studied. IL 1α and TNF‐α reached maximal levels within 6 h of stimulation, whereas IL 1β reached maximal levels between 12 and 16 h. IL 1α remained primarily cell associated (80%) for the first 24 h. After 48 h, extracellular IL 1α exceeded cell‐associated levels. IL 1β was primarily secreted (80%), appearing in the extracellular fluid within 6 h. TNF‐α appeared in the extracellular fluid within 1 h of incubation, with<10% cell associated at any time during the 48 h of incubation. Although the three cytokines share many biological activities, this study provides evidence that MNC IL 1α is predominantly a cell‐associated cytokine acting on a cell‐cell basis, whereas IL 1β a

ISSN:0014-2980    

DOI:10.1002/eji.1830190903

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe human immunodeficiency virus type 1 (HIV‐1) induces a strong cytotoxic T lymphocyte (CTL) response in humans following infection. HIV‐specific CTL can be detected directly in the blood and lungs of infected patients, and can be expandedin vitroby stimulation with autologous HIV‐infected lymphoblasts. Furthermore, CTL specific for HIV envelope glycoprotein gp160 have been obtained in mice by immunization with recombinant vaccinia virus (VV) that carry the HIVenvgene. In this study, we show that mice also produce strong CTL responses to gag and nef proteins following immunization with VV recombinants, thus providing a convenient model system to study T lymphocyte immunity to defined HIV antigens. To determine the specificity of circulating HIV‐immune CTL in humans, a panel of doubly transfected mouse P815 tumor cells was produced which express the human HLA‐A2 or HLA‐A3 transplantation antigen gene and one HIV‐1 gene (env, gag or nef). Using these cells as targets to CTL, we show that HIV‐infected humans carry co‐existing CTL sub‐populations of different specificities. Each subpopulation appears to vary in intensity among different individuals. Surprisingly, CTL specific for regulatory, non‐structural nef protein appear to be a major constituent of the human i

ISSN:0014-2980    

DOI:10.1002/eji.1830190904

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have identified in earlier studies two Vδrearrangements corresponding to a 4.5‐kb Eco RI fragment detected with a Vδ1 probe and to a 7‐kb Eco RI band detected with a Vδ2 probe. These rearrangements have been found in two human T cell clones, F6C7 and G6, displaying surface phenotypes unfrequent in human peripheral blood, namely TiγA+BB3‐(F6C7) and TiγA‐BB3+(G6). Herein, we report the sequences of the functional transcripts encoded by these rearranged genes and show that the 4.5‐and the 7‐kb Eco RI fragments correspond to V1/D3/Jδ3 and to V2/D3/Jδ3 recombinations, respectively. In addition, we have sequenced the V2/D3/J1/Cδtranscripts expressed in two clones, AB12 and VTC, which have a TiγA+BB3+surface phenotype corresponding to that of most γ/δ peripheral lymphocytes. Analyses of the δ transcripts expressed by these four cells further strengthen the hypothesis that anti‐BB3 and anti‐δ‐TCS‐1 monoclonal antibodies recognize a Vδ2‐ and a V1/(D)/Jδ1‐encoded epitope, respectively. Sequence of the γ transcripts expressed by AB12 and F6C7 cells shows that they encode a V9/JP/Cγ1 chain. Finally, we confirm that non‐combinatorial diversity in the γ and δ proteins is generated by both junctional flexibility and N

ISSN:0014-2980    

DOI:10.1002/eji.1830190905

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractIn humans, lymphocyte adhesion to cells is mediated by the protein heterodimer CD11a/CD18 (Leu‐CAMa, LFA‐1) and its ligand CD54 (ICAM‐1). Although the murine CD11a/CD18 is well characterized, the mouse homologue of human ICAM‐1 has not been identified. In the present study a rat monoclonal antibody to the murine lymphocyte activation antigen MALA‐2 was found to inhibit in a dose‐dependent manner the phorbol ester‐enhanced aggregation of mouse lymphoblasts, an adhesionspecific assay, and hence to define an adhesion molecule. By immunofluorescence flow cytometry the antigen expression was low on spleen cells but it largely increased after stimulation with mitogens. The antigen was expressed by some, but not all, lymphoid cell lines, and myelomonocytic and mastocytoma cells were also positive. In frozen tissue sections MALA‐2 was mainly detected on germinal center B cells, dendritic cells, macrophages and vascular endothelium, including high endothelial venules. Cell surface labeling followed by immunoprecipitation and gel electrophoresis indicated that the antigen is a sialoglycoprotein which has a relative molecular mass of 95 kDa and displays a faster electrophoretic mobility under nonreducing conditions. The function, cellular distribution and molecular properties of MALA‐2 are indistinguishable from thos

ISSN:0014-2980    

DOI:10.1002/eji.1830190906

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractHuman T cell receptor (TcR) γδ displays a variety of protein forms. Disulfide‐linked (type 1) or non disulfide‐linked (type 2) receptors occur, with γ chains encoded by the Cγ1 or the Cγ2 gene segment, respectively. Exon 2 of Cγ2 may either be duplicated or triplicated (type 2a or 2b receptors). TcR γ chains differ in molecular mass and charge between type 1 and type 2 receptors. The δ chains as well as the γ chains have different structural properties between receptor types. This cannot be due to the use of different Cδgene segments, since the genome encodes only one. To understand the genetic basis of this dichotomy in γ/δ combinations, rearrangement and expression of Vγ, Jγ, Cγand Vδgene segments were determined in TcR γ/δ+clones derived randomly from peripheral blood of normal donors. Most clones used Cγ1, a minority Cγ2. The different protein properties of receptor types could be explained by the nonrandom expression of Vγ(Jγ) and Vδgene segments. Type 1 receptors preferentially used γ chains encoded by the Vγ9 and Jγ1.2 gene segments together with δ chains encoded by Vδ2. In type 2a receptors, Vγ9 was not predominant; often other Vγgene segments were employed, but then in high frequency in coordination with Vδ1. Reactivity of the clones with monoclonal antibodies anti‐TiγA, BB3 and δ‐TCS‐1 correlated with the expression of the Vγ9, Vδ2 and Vδ1 gene segments, respectively. Therefore, Vγand Vδuse in TcR γ/δ+cells from peripheral blood of eight healthy individuals, including the two donors of the clones, could be determined tentatively by double immunofluorescence. Indeed, the Vγ9‐Vδ2 combination was predominant, while the Vγ9‐Vδ1 and particularly the Vγ9‐“Vδother” combination was rare. These data indicate that the TcR γδ repertoire in peripheral blood of normal individuals is largely dependent on

ISSN:0014-2980    

DOI:10.1002/eji.1830190907

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this study, we investigated whether the phenotype‐related differentiation of human 2H4+(CD45R) naive cells to 2H4‐(CDw29) memory CD4 cells corresponded to modulation of interleukin (IL) 2, IL 4, interferon (IFN)‐γ and granulocyte‐monocyte colony‐stimulating factor (GM‐CSF) gene expression, a phenomenon which might correlate to the distinct functional activities of naive cells or memory cells. To mimicin vitroCD4 T cell subset differentiation, freshly isolated 2H4+and 2H4‐CD4 cells were stimulated with the anti‐CD3 antibody (Leu‐4), expanded in IL 2‐containing medium and restimulated with Leu‐4 after 7 and 13 days. Absence of monocyte‐T cell interaction was compensated by adding monocyte supernatant to the culture medium and by cross‐linking the anti‐CD3 antibodies with goat anti‐mouse antibody coated on culture dishes.It has been previously shown thatin vitrostimulated 2H4+cells acquire CDw29 surface antigens. Measurement of lymphokine gene expression by dot‐blot hybridization revealed that although stimulated 2H4+cells proliferated less than stimulated 2H4‐cells, and expressed less actin mRNA, they expressed more IL 2 but less IL 4 and GM‐CSF than 2H4‐cells. No significant difference was observed between the two subsets for the expression of IFN‐γ. If subsets were restimulated with Leu‐4 antibodies, expression of IL 2 was decreased and expression of IL 4 was increased in both subsets; however, the differences among the subsets persisted. They were even more enhanced for IL 2 but less pronounced for GM‐CSF.Thus, in spite of phenotype conversion, CD4 T cell subsets maintained a dis

ISSN:0014-2980    

DOI:10.1002/eji.1830190908

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractWe have derived a number of transgenic mouse lines which express the human major histocompatibility complex class I gene HLA‐A2.1. Two lines carry the complete human HLA‐A2.1, the others bear a recombinant gene in which the HLA‐A2.1 coding regions are fused to the H‐2Kbpromoter. Analysis of transgenic spleen cells by immunofluorescence demonstrates that these mouse cells express HLA‐A2.1 on their surface in association with mouse β2‐microglobulin (β2m), confirming that HLA‐A2 does not require human β2m to be expressed at the cell surface. The cells contain more HLA mRNA than endogenous H‐2 class I mRNA. There is also a large pool of non‐β2m‐associated HLA heavy chain inside the cell. In contrast the amount of HLA: β2m complex is low. Thus, in transgenic mice HLA‐A2 seems to compete poorly with H‐2 heavy chains for mouse β2m.The HLA‐A2.1 transgenic mice do not produce influenza‐virus‐specific cytotoxic T cells (CTL) restricted to the HLA transgene, at least in sufficient numbers to be measured in a direct bulk CTL assay. The dominance of H‐2‐restricted clones may be the result of quantitative rather than qualitative factors. However, HLA‐A2.1 transgenic spleen cells are effective in stimulating an allogeneic CTL response in normal mice. This response is not H‐2 restricted. Cold target inhibition studies show that there are at least two populations of CTL, one of which is specific for HLA‐A2.1 on mouse cells. This result suggests that at least some allo‐CTL are directed against major

ISSN:0014-2980    

DOI:10.1002/eji.1830190909

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractAn HLA‐DR product encoded by the HLA‐DRw13/Dw19 haplotype has been identified as the HLA class II molecule involved in antigen presentation to several influenza‐specific helper T cell clones. Three different functional sites were identified on this molecule by comparing the structure of HLA‐DR products of known sequences and their ability to efficiently present foreign antigen to the T cell clones. These functional sites were mapped on the recently proposed three‐dimensional structure of HLA class II molecules. From their position, these sites are all potentially involved in HLA‐peptide interaction and capable of affecting the binding and/or the conformation of the foreign peptide. This suggests that polymorphic residues essential in major histocompatibility complex restriction are mostly involved in pept

ISSN:0014-2980    

DOI:10.1002/eji.1830190910

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractA sensitive assay utilizing enzyme‐linked immunosorbent assay methodology has been developed for the quantitation of single cells secreting interferon (IFN)‐γ or tumor necrosis factor (TNF). Cloned T cells or cells from lymphoid organs were stimulated with antigen, concanavalin A, or phorbol myristate acetate and ionomycin in microwells coated with antibodies specific for IFN‐γ. Discrete “spots” overlying areas where cells secrete IFN‐γ were then developed by incubation with a second antibody to IFN‐γ, followed by an enzyme‐labeled antibody conjugate and substrate. Similarly, using TNF‐specific antibody reagents, TNF‐secreting cells were detected and quantitated in cell populations obtained from normal lymphoid tissues, bone marrow and peripheral blood, following activation with phorbol myristate acetate and ionomycin. Provided specific antibodies are available, this method has the potential to measure the frequency of cells

ISSN:0014-2980    

DOI:10.1002/eji.1830190911

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY