ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02640.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02641.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Interaction of the CD80 (B7‐1) and CD86 (B7‐2) molecules on antigen presenting cells with the receptors CD28 and CTLA‐4 on T cells generates signals important in the regulation of immune responses. Because this receptor system involves multiple receptor‐ligand interactions, determining the function for individual receptors has been difficult. One approach is the use of antibodies and their derivatives with singular specificity as substitute ligands to explore the activities of these molecules. We have constructed recombinant mono‐and bi‐specific sFv molecules specific for the CD28 receptor that are capable of binding and generating costimulatory signals to activate T cells. We demonstrate that these soluble molecules are capable of higher levels of costimulation than soluble CD80Ig at equivalent concentrations. We also constructed artificial adhesion receptors on the cell surface using two different CD28‐specific sFvIgs fused to the CD80 cytoplasmic and transmembrane domains. In this report, we compared costimulation by a soluble bispecific (αCD28‐α6) single chain sFvIg fusion protein to that generated by L6 antigen positive (L6+) H3347 tumor cells transduced with cell surface expressed forms of aCD28 sFv's. We show that the bispecific protein can target potent CD28 costimulatory activity to L6+ tumor cellsin vitro. We also show that transfection of the cell surface forms of the two different CD28 sFvIgs into H3347 tumor cells allows them to generate significant costimulatory signals to activated T cells. Finally, we demonstrate that tumor cell presentation of either the soluble bispecific or transduced cell surface sFv generate similar costimulatory effects resulting in

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02642.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Signaling by the CD28 T cell costimulatory receptor is known to involve recruitment and activation of phosphatidylinositol 3‐kinase (PI3‐kinase) which is dependent upon phosphorylation of tyrosine 173 of the CD28 cytoplasmic tail, present in a YMNM motif. However, whether this phosphorylation is required for CD28 costimulation and whether or not phosphorylation of any of the other three tyrosines of the CD28 cytoplasmic tail (tyrosines 188, 191 and 200) is also important for CD28 induced responses is unclear. To address this we examined the ability of chimeric receptors, consisting of the extracellular plus transmembrane membrane domain of human CD8α linked to different mutated human CD28 cytoplasmic tails, to induce IL‐2 secretion in Jurkat T leukemia cells in the presence of PMA and ionomycin. A receptor in which tyrosine 173 of the CD28 tail was mutated to phenylalanine was able to induce IL‐2. By contrast, receptors which contained single tyrosine 188, 191 or 200 to phenylalanine substitutions were unable to induce IL‐2. These results imply that in this system phosphorylation of tyrosine 173 and hence activation of PI3‐kinase is not required for CD28 induced IL‐2 secretion. Further, they imply that phosphorylation of each of tyrosines 188, 191 and 200 is necessary for this response. Despite an apparent requirement for phosphorylation of all three of these tyrosines, however, receptors which contain tyrosine only at positions 191 or 200 and a truncated receptor which does not contain tyrosine 200 induce normal IL‐2. These last findings, therefore, illustrate the complexity of CD28 mediated ac

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02643.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Interleukin‐12 (IL‐12) is an important cytokine in the control of cell‐mediated immunity. We have previously shown that endogenous IL‐12 plays a role in the development of human allogeneic response. In the present study, we investigated the relationship between Cyclosporin A (CsA)‐inhibitory effect and IL‐12 pathway during human alloreaction in vitro. CsA addition at the sensitizing phase of primary mixed lymphocyte reaction (MLR) resulted in the inhibition of both p40 and p70 IL‐12 production in a dose‐dependent manner. In contrast, CsA had no effect on IL‐12‐receptor β1 chain (IL‐12 Rβ) expression in T cells induced upon allogeneic activation. Addition of exogenous IL‐12 significantly restored CsA‐inhibited alloreactive cytotoxic T lymphocyte (CTL) generation and had a marginal effect on T cell proliferative response. The IL‐12‐induced restoration of CTL generation was IFNγ‐mediated, as it was significantly altered when anti‐IFNywas added. The restoration of CTL activity by exogenous IL‐12 correlated with the capacity of this cytokine to partially restore granzyme B mRNA expression in alloreactive CTL. This study indicates that inhibition of IL‐12 production is a novel additional mechanism for the inhibitory effect of CsA on the developmen

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02644.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

ICAM‐3/CD50 is a recently described LFA‐1 counter receptor that seems to play an important role in the initiation of immune responses. In this study we have examined the expression of ICAM‐3/CD50 in a large series of human neoplasms including 101 Non‐Hodgkin's lymphomas (NHL), 26 Hodgkin's disease, and 38 solid tumors to define the distribution patterns of this molecule in malignant neoplasms and their possible correlation with clinical and pathological characteristics of the patients. In NHL, ICAM‐3/CD50 was expressed in almost all the tumors with a tendency to be lost in high grade lymphomas. Reed‐Sternberg cells and their variants in Hodgkin's disease were always negative independently of the histological subtype of the disease. No expression was observed in tumor epithelial cells of the 38 solid tumors examined. Strong endothelial cell staining was observed in 31% of the NHL and 31% of Hodgkin's disease. ICAM‐3 expression in these cases was restricted to small tumor vessels. ICAM‐3 expression in endothelial cells of NHL was significantly more frequent in high grade (40%) than in low grade lymphomas (14%) (p=0.012). In addition, tumor vessels were also positive in 29% of solid rumors independently of the histological type. No correlation was observed between ICAM‐3 expression in tumor or endothelial cells and other clinical and pathological characteristics of the patients. These findings indicate that ICAM‐3 expression in human tumors is restricted to hematological neoplasms with a tendency to be lost in high grade lymphomas and Hodgkin's disease. ICAM‐3 is also expressed by endothelial cells from tumor‐associated neovascularization in both ly

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02645.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

Cytolysis by NK cells that possess the NKB 1 killer cell inhibitory receptor is inhibited by target cell expression of Bw4+ HLA‐B molecules. The inhibitory effect can be prevented by addition of mAbs which block recognition of class I molecules by NKB 1. The epitopes recognized by two anti‐class I mAbs, DX15 and DX16, which inhibit the interaction of NKB 1 with class I have been characterized. Binding of DX15 and DX16 to class I allotypes was investigated by flow cytometric analysis of transfected cell lines which express just one HLA‐A, B, or C allele, and by immunoprecipitation of class I molecules from HLA typed B‐lymphoblastoid cell lines, followed by isoelectric focusing. The DX16 mAb recognizes class I allotypes which possess alanine at position 71 of the α1helix, and therefore has a specificity resembling that of the ME 1 mAb but with broader specificity. Class I recognition by DX15 is affected by polymorphisms of the C‐terminal part of the α1helix, and the N‐terminal part of the α2helix. DX15 thus appears to recognize a complex epitope near the end of the peptide binding groove which may be conforma‐tionally determined. Both antibodies are as effective as the anti‐NKB 1 mAb (DX9) in preventing class I recognition by the NKB 1 receptor. DX16 also blocked recognition by a B*0702 allospecific CTL clone, wh

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02646.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The killer cell inhibitory receptors (KIRs) are surface glycoproteins expressed by natural killer (NK) cells and some T cells. They recognize polymorphic human HLA class I molecules. Two families of KIRs have been identified and named p58 and p70. The p58 family of genes encode type I membrane proteins with two extracellular immunoglobulin (Ig) domains, while the p70 genes have three Ig domains. We here report the cloning and characterization of a novel KIR cDNA obtained from tumor cell lines with NK reactivity (YT and NK‐92). This gene is also expressed in the normal cell line NK 3.3 and in NK cells obtained from some but not all normal donors. The clone, KIR103AS, has an open reading frame consistent with a KIR with two extracellular Ig domains, a transmembrane region and a 114 amino acid long cytoplasmic domain containing a single src homology 2 (SH2) binding motif. The membrane distal Ig domain of KIR 103AS has highest homology with the first Ig domain of p70 KIRs and differs significantly from the first Ig domain of p58 KIRs. The second, membrane proximal Ig domain of KIR103AS has similar and high homology with the membrane proximal Ig domains of both p70 and p58 KIRs. The extracellular domains of KIR 103AS therefore share characteristic features with both p70 and p58 genes: the domain structure is identical to p58 KIRs but the sequence homology matches closely with p70 KIRs. The putative transmembrane and cytoplasmic domains are distinctly different from all previously reported KIR cDNA

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02647.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The expression of Fas antigen at the surface of renal cell carcinoma and the susceptibility to Fas‐mediated lysis by a tumor specific CTL clone were investigated. Renal cell carcinoma cell lines expressed Fas antigen and were susceptible to apoptosis mediated by antibodies to Fas/APO1. Using RT‐PCR, we further showed that these cell lines expressed mRNA for Fas deleted transmembrane region, corresponding to a soluble form of Fas/APO‐1. To investigate the role of the Fas/FasL pathway in the cytotoxic response against RCC cells, we analyzed the induction of Fas‐L on a tumor specific T cell clone (CTL 8C2), previously generated against one RCC cell line. Fas‐L expression on CTL 8C2 was detected by RT‐PCR after stimulation with autologous tumor cells. However, the cytotoxic activity of CTL 8C2 was completely abolished when EGTA was added, suggesting that the cytolysis was mainly mediated by a Ca++‐dependent pathway, perforin/g

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02648.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

The antigens encoded by the major histocompatibility complex (MHC) are cell surface glycoproteins that play a fundamental role in the regulation of the immune response. Anomalous MHC expression in tumor cells has been viewed as an important feature to escape tumor recognition by immune cells. Low or absent MHC class I expression as well as ectopic MHC class II expression have been often observed to correlate with high grade malignancy and metastatic potential in a variety of human cancers. To date, very little investigation of MHC (HLA in man) class I and class II expression inhuman pancreatic cancer has been reported. We investigated this aspect on frozen sections of 8 pancreatic adenocarcinomas and 18 establishedin vitrocell lines. HLA class I was expressed in all but two cancers whereasde novoHLA class II expression was detected in 3 of 8 cancers. Interestingly, a hierarchy in the expression of the various subsets of HLA class II was found with HLA‐DR>‐DP>‐DQ. Results on cell lines strongly resembled the ones obtained in cancer tissues. However, a peculiar feature was observed in certain cell lines. HLA class II antigens were expressed in only a few cell lines and in some of them a mixed population of positive and negative cells was found. Sorting and cloning of the two populations confirmed the existence of tumor cell clones with stable and distinct HLA class II phenotype. Taken together, these results indicate the cellular heterogeneity of pancreatic cancer cells with regard to the qualitative and quantitative expression of major histocompatibility complex genes, and may provide new insights for a better understanding of the tumor‐host relationships in this extremely severe form of ne

ISSN:0001-2815    

DOI:10.1111/j.1399-0039.1996.tb02649.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY