摘要:

AbstractMurine acquired immunodeficiency syndrome (MAIDS) is caused by a defective murine leukemia virus. The disease is characterized by abnormal lymphoproliferation, impaired T and B cell function and aberrant regulation of cytokines. Both T and B lymphocytes show activated phenotypes, but undergo apoptotic death with characteristic DNA fragmentation. These results indicate the presence of a continuous activation death pathway of the lymphocytes in MAIDS. Overexpression of the bcl‐2 transgene in lymphocytes showed no effect on the apoptotic cell death or on the development of the disease. In contrast, mice carrying mutations in either Fas or Fas ligand exhibited accelerated progression of the disease upon infection with MAIDS virus. These results suggest the involvement of Fas‐Fas ligand system in the pathogenesis of MA

ISSN:0014-2980    

DOI:10.1002/eji.1830250902

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe glycosylphosphatidylinositol (GPI)‐anchored protein Thy‐1 is one of the most abundant molecules expressed on the surface of rat mast cells and rat basophilic leukemia cells, RBL‐2H3. Antibody‐mediated aggregation of Thy‐1 induces in these cells release of secretory components; so does aggregation of the receptor with high affinity for IgE (FcϵRI). To examine whether there is any relationship between Thy‐1‐ and FcϵRI‐mediated activation, we have isolated from mutagenized RBL‐2H3 cells a variant cell line deficient in the expression of surface FcϵRI, and analyzed its ability to be activated by an antibody to Thy‐1. Northern and immuno‐blot analyses revealed that the variant cells were deficient in the expression of a structural or a regulatory gene for FcϵRI γ subunit. The cells did not respond by release of secretagogues and protein‐tyrosine phosphorylation to IgE and antigen and anti‐FcϵRI monoclonal antibody (mAb) but their response to anti‐Thy‐1.1 mAb and calcium ionophore A23187 was retained. Transfection of the cloned FcϵRI γ subunit into the variant cells restored the surface expression of FcϵRI and responsiveness to both the antigen and anti‐FcϵRI mAb but had no effect on responsiveness to anti‐Thy‐1 mAb. The combined data indicate that aggregation of surface Thy‐1 glycoproteins activates a metabolic pathway which is independent of the presence of

ISSN:0014-2980    

DOI:10.1002/eji.1830250903

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractNatural killer (NK) cells preferentially express several genes of the C‐type lectin superfamily which have been implicated in the regulation of NK cell function. We demonstrate that CD94 is a type II membrane protein encoded by a unique gene of the C‐type lectin superfamily. While homology of CD94 with the NK cell‐associated NKR‐P1 and NKG2 C‐type lectin genes is limited to the structural motifs conserved in the carbohydrate recognition domain, all of these genes are on human chromosome 12, the syntenic of mouse chromosome 6, where genes of the NK complex (NKR‐P1andLy‐49) are located. An unexpected feature of CD94 is the essential absence of a cytoplasmic domain, implying that association with other receptors may be necessary for the function of

ISSN:0014-2980    

DOI:10.1002/eji.1830250904

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe cytokine lymphotoxin (LT)α is known to play a role in B cell activation. As the engagement of the B cell antigen CD40 is known to lead to B cell proliferation and differentiation, we studied LTα expression in human B cells after CD40 ligation. We demonstrate that anti‐CD40 monoclonal antibody (mAb) induces strong LTα mRNA and surface expression in human tonsil B cells. Induction of LTα mRNA and surface expression by CD40 ligation is inhibited by the protein tyrosine kinase (PTK) inhibitors herbimycin and genistein in a dose‐dependent manner. The protein kinase C (PKC)‐specific inhibitors sphingosine and bisindolylmaleimide caused negligible inhibition of anti‐CD40‐induced LTα mRNA and surface expression. No inhibition is observed with the protein kinase (PKA) inhibitors H89 and HA1004. Cross‐linking of the transmembrane phosphatase CD45 to CD40 by using goat‐anti‐mouse F(ab')2fragments strongly inhibits CD40‐mediated LTα expression in human B cells, confirming the role of PTK activation in CD40‐mediated induction of LTα expression. Inhibitors of the serine/threonine protein phosphatases PP1 and PP2A, okadaic acid and calyculin induce LTα mRNA expression. In contrast, cyclosporin A, an inhibitor of the serine/threonine phosphatase calcineurin has no effect on anti‐CD40‐induced LTα expression. These results suggest that induction of LTα expression in B cells following engagement of CD40 involves activ

ISSN:0014-2980    

DOI:10.1002/eji.1830250905

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractAn early consequence of T cell activation is an increase in intracellular calcium concentration. Recent advances in video laser microscopic techniques enable the examination of individual cells over time following stimulation. Such studies have revealed that cells can undergo qualitatively distinct patterns of calcium mobilization, suggesting that different patterns of calcium flux may be associated with different signaling pathways and may differentially affect late events in cell activation. In this report, we identify distinct patterns of calcium mobilization in CD4+T cells following the antibody‐mediated cross‐linking of either CD3 or CD4, or following the cross‐linking of both CD3 and CD4 simultaneously. These effects can be further modified by the cross‐linking of CD45. We find that antibody cross‐linking of CD3 alone induces a single spike in the vast majority of cells shortly after the addition of the cross‐linking antibody. In contrast, cross‐linking CD4 alone induces a delayed pattern of repetitive calcium spikes which are decreased in amplitude compared to CD3 cross‐linking. Simultaneous cross‐linking of CD3 and CD4 induces a sustained increase in intracellular calcium mobilization which is dependent on the presence of extracellular calcium. This sustained increase in intracellular calcium concentration is also seen following physiologic cross‐linking of CD3 and CD4 after T cell interaction with specific antigen and antigen‐presenting cells. Finally, the simultaneous cross‐linking of CD45, CD3 and CD4 abrogates the sustained increase in calcium seen following CD3 and CD4 cross‐linking. These results suggest that the qualitative nature of T cell receptor signaling can be modulated by the molecular association of other signaling molecules, which may be part of the T cel

ISSN:0014-2980    

DOI:10.1002/eji.1830250906

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractE‐selectin is a cytokine‐inducible membrane glycoprotein capable of mediating adhesion of leukocytes to endothelial cells. It is highly glycosylated, containing 11 sites for N‐linked glycosylation. N‐Glycosylation of E‐selectin was analyzed by endoglycosidase treatment. Analysis of immunoprecipitated E‐selectin from human umbilical vein endothelial cells (HUVEC) by polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate showed that E‐selectin was completely resistant to endoglycosidase H, but sensitive to peptide N‐glycanase F digestion. This suggested that all N‐linked oligosaccharide chains were of the complex type. The role of N‐linked glycosylation in surface expression and secretion of E‐selectin was studied using interleukin‐1‐stimulated HUVEC, cultured in the presence of the soluble glycosylation inhibitors tunicamycin or castanospermine. Cell surface expression was analyzed by indirect flow cytometry. N‐Glycosylation was blocked by tunicamycin, and resulted in a significantly reduced surface expression of E‐selectin, whereas castanospermine only marginally reduced E‐selectin expression. The deglycosylated forms of E‐selectin were also found to be fully capable of mediating adhesion of HT‐29 cellsin vitro.In conclusion, these studies show that E‐selectin is heavily glycosylated with complex type N‐linked oligosaccharides and that N‐glycosylation is important for expression

ISSN:0014-2980    

DOI:10.1002/eji.1830250907

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe have made a monoclonal anti‐CD44 antibody which is able to activate the leukocyte integrin CD11a/CD18. Activated T cells strongly aggregated, and the aggregation was shown to be intercellular adhesion molecule (ICAM)‐1 (CD54) and ICAM‐2 (CD102) dependent. Using purified ICAM coated on plastic, only binding to ICAM‐1 was increased by the CD44 antibody, whereas activation by phorbol ester increased binding to both ICAM‐1 and ICAM‐3. The binding to ICAM‐2 was not affected by either treatment. These findings show that the CD11a/CD18 integrin can be activated in a ligand‐specific manner by eng

ISSN:0014-2980    

DOI:10.1002/eji.1830250908

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractInterleukin (IL)‐10 down‐regulates HLA class II molecules, whether constitutively expressed or up‐regulated by interferon‐γ or IL‐4 on monocytes but not on B lymphocytes. In this study we show that IL‐10 does not inhibit HLA class II expression induced by the combination granulocyte/macrophage colony‐stimulating factor and IL‐4 on monocytes, although it simultaneously abrogates the expression of CD1 molecules induced by the same combination of cytokines. CD1 molecules can act as element of genetic restriction for CD4−CD8−T lymphocytes, and the suppression of CD1 expression by IL‐10 abolished antigen presentation to CD1‐restricted CD4−CD8−T cell receptor‐positive T cells. Although HLA class II expression was not down‐regulated by IL‐10, the antigen specific proliferative response of CD4+T cells was nevertheless decreased. This was not caused by down‐regulation of known co‐stimulatory molecules such as B7.1, B7.2 and ICAM‐1. IL‐10 decreased the antigen specific proliferative response further by directly influencing the T lymphocytes. Our results indicate that IL‐10 exerts some of its immunoregulatory functions by differential modulation of antigen presenting molecules,

ISSN:0014-2980    

DOI:10.1002/eji.1830250909

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractCD34, a stem cell marker, has been shown to be expressed on human CD3−CD4−CD8−(triple‐negative; TN) thymocytes. Phenotypic and functional analyses suggest the following differentiation sequence: CD34+1−3−4−8−→ CD34+1+3−4→8−→ CD34−1++3−4+8 → CD34−1++3−4+8+. In this report, we examined cytokine receptor gene expression on these subsets by reverse transcription‐polymerase chain reaction analysis (RT‐PCR). We were able to detect interleukin‐7 receptor (IL‐7R), c‐kit and IL‐2Rγ in all CD34+thymocyte subsets, consistent with previous functional studies. We found IL‐1R, granulocyte/macrophage colony‐stimulating factor receptor‐α and IL‐4R transcripts in CD3−and CD34+subsets. Secondly, we investigated T cell receptor (TCR)‐δ and ‐β gene rearrangement and transcription in CD34+thymocytes. Our results show that a full‐length TCR‐δ transcript and the recombination activating genes RAG‐1 and RAG‐2 mRNA were already expressed in the CD34+1−subset. Mature Vβ‐containing TCR transcripts were also detected in the CD34+1+subset, but not in the CD1−fraction. Furthermore, PCR analysis of D‐Jβ gene rearrangements showed that ≥ 70% of CD34+1−cells are in a TCRβ ge

ISSN:0014-2980    

DOI:10.1002/eji.1830250910

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe T cell receptors (TCR) in HLA‐B27 (B*2705) alloreactivity were analyzed in cytotoxic T lymphocytes (CTL) from two individuals. Non‐random usage was found in Vβ, N+Dβ, Vα, and Jα, but not in Jβ segments or Nα‐regions. Vβ segments from homology subgroup 4 were predominant and not associated to a particular donor or fine specificity, suggesting involvement in recognizing the HLA‐B27 molecule. In contrast, preferential Vα usage was associated with particular individuals and fine specificities, indicating distinct Vβ and Vα recruitment and contribution to allorecognition. Recurrent N+Dβ motifs and Jα segments, even from different donors, limited junctional diversity, suggesting that CDR3 usage was determined by the alloantigenic epitope independently of individuals. TCR were selected differently at various levels, as indicated by the following findings. Four clonotypes with similar fine specificity had identical β and unrelated α chains. Similar α were associated with unrelated β chains, and vice versa. CTL using Vβ subgroup 4 did not globally show concomitant predominance of other TCR elements. Vα7, one of the preferred Vα segments, was always associated with Vβ subgroups other than 4. Sometimes, a TCR showed homology in elements of one chain to a second TCR or group of TCR, and to another in the other chain. These results are best explained by differential selection of TCR elements by different epitopes, providing a key to the inner structure of a

ISSN:0014-2980    

DOI:10.1002/eji.1830250911

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY