摘要:

AbstractA human erythroleukemic cell line (K562) that does not normally express β2 integrins has been transfected with the genes encoding these integrins. The resulting cell lines show minimal background adhesion but can be stimulated to bind to appropriate substrates when activated with either of two different antibodies to CD18. The two antibodies appear to generate different ligand binding states in LFA‐1 such that different members of the ICAM family are recognized. Antibody‐activated complement receptor type 3 and p150,95‐transfected cells bind protein‐coated surfaces, although they require slightly different activation conditions for optimal

ISSN:0014-2980    

DOI:10.1002/eji.1830250302

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractFlow cytometric analysis of human peripheral blood T lymphocytes demonstrated that the majority of the CD4+cells were CD29+or CD45RO+“mature” cells while the CD8+cells were primarily CD45RA+“naive” cells. After an initial separation into CD4+and CD8+cells and a secondary separation into CD45 subsets, lymphokine secretion was assessed after phorbol 12‐myristate 13‐acetate and ionomycin or fixed anti‐CD3 stimulation. Within the respective CD45 subsets, CD4+cells produced more interleukin (IL)‐2, IL‐4, and IL‐6; but the CD8+cells secreted more interferon‐γ and granulocyte/macrophage‐colony‐stimulating factor. Tumor necrosis factor‐α secretion was similar in the matched CD45 subsets. Northern analysis revealed a parallel pattern of lymphokine mRNA expression in the four lymphocyte subsets. These results suggest that human CD8+peripheral blood lymphocytes have a significant capacity to secrete lymphokines, and that the low lymphokine production observed in unseparated CD8+cells reflects the higher percentage of

ISSN:0014-2980    

DOI:10.1002/eji.1830250303

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractSoluble interleukin‐4 receptors (sIL‐4R) are truncated IL‐4R molecules that are secreted into biological fluids. To gain an insight into the mechanisms that control sIL‐4R synthesisin vivoand their role in the regulation of immune responses, the expression and secretion of sIL‐4R in mice infected withSchistosoma mansoniwas studied. Splenocytes from infected animals responded to schistosomal antigen preparations with increased production of both IL‐4 and sIL‐4R. The synthesis of sIL‐4R by spleen cells peaked at 8 weeks following infection and coincided with maximum levels of sIL‐4R in serum and sIL‐4R‐specific mRNA in the liver of infected mice. The expression of IL‐4‐specific mRNA in the liver was different from that of IL‐4R, reaching its peak approximately 2 weeks earlier. A relationship between sIL‐4R production and the development and activation of Th2 cells was suggested by the findings that: (a)in vivoadministration of anti‐IL‐4 antibodies (11B11) impaired the ability of splenic cells to secrete either IL‐4 or sIL‐4R; and (b) splenic cells from mice vaccinated with irradiated cercariae, which tend to develop much weaker Th2 responses than mice injected with live cercariae, expressed reduced levels of sIL‐4R when challenged with schistosomal antigens. Moreover, a direct role for IL‐4 in regulating the expression of sIL‐4R was suggested by the ability of anti‐IL‐4 antibodies to inhibit sIL‐4R synthesisin vitro. These data provide the first evidence demonstrating that the production of sIL‐4Rin vivois up‐regulated during immune responses, especially during those characterized by the development and activation of Th2 cells and IL‐4 secretion. The association between sIL‐4R and IL‐4 syntheses is consistent with a potentia

ISSN:0014-2980    

DOI:10.1002/eji.1830250304

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractMolecular and cellular requirements for antigen‐specific isotype switch of human B cells have been investigated by mimicking signaling occurring in germinal centers. Peripheral blood mononuclear cells from healthy seronegative blood donors were first primary immunizedin vitro, using a synthetic immunogen containing both a T and B cell epitope, which generated specific IgM‐secreting B cells. We used the apex of the V3 loop of gp120 as B cell epitope linked to a promiscuous T helper epitope from tetanus toxin. In parallel, CD4+T helper cell clones specific for the T epitope of the immunogen were established. In a secondaryin vitrostimulation period, we co‐cultured the antigen‐specific T and B cells on CD32‐transfected fibroblasts, together with an anti‐CD40 monoclonal antibody. This resulted in isotype switching and human antigen‐specific, IgG‐secreting B cells were detected. This response was strictly dependent upon the presence of autologous T helper cells and the immunogen. Antigen‐specific human B cells derived from this primary and secondaryin vitroimmunization were subsequently subjected to electrofield‐induced somatic cell hybridization and hybridomas secreting human anti‐V3 IgG monoclonal antibodies were isolated. One human antibody was further characterized and shown to be specific for the immunizing antigen with an affinity constant of 24 nM. This antibody also effectively neutralized different isolates of HIV‐1, achieving a 50% neutr

ISSN:0014-2980    

DOI:10.1002/eji.1830250305

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractWe reported previously that the mouse tumor P815 expresses four distinct antigens (A, B, C, D) recognized by syngeneic cytolytic T lymphocytes (CTL). A fifth P815 antigen (E) was identified by means of a CTL clone derived from tumor‐infiltrating lymphocytes. We compared a number of mice for the orientation of their CTL response with respect to the various P815 antigens. Lymphocytes from mice inoculated subcutaneously with living P815 cells were stimulatedin vitrowith tumor cells and the resulting CTL were tested against targets expressing either antigens A and B or antigens C, D and E. Many mice had an asymmetrical response, some producing CTL directed almost exclusively against antigens A, B and others producing CTL directed almost exclusively against C, D. E. When mice were inoculated into two separate sites, different orientations in the responses of the two local lymph nodes were often observed, suggesting that individual differences in the orientation of the anti‐P815 CTL response do not result from preexisting differences between the animals. Asymmetrical CTL responses persisted in mice that were given a second injection of tumor cells. A possible interpretation of our results is that the major component of the CTL response is made of the progeny of a very small number of CTL precursors that happen to be the first to be stimulated by the tumor antig

ISSN:0014-2980    

DOI:10.1002/eji.1830250306

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractSeveral cytokines, in particular tumor necrosis factor‐α (TNF‐α) and interferon‐γ (IFN‐γ), have been shown to be responsible for pathological reactions which may lead to shock and death observed in infection with Gram‐negative bacteria and in response to endotoxins (lipopolysaccharides, LPS). Priming of mice with the avirulent Bacille Calmette Guérin (BCG) vaccine strain ofMycobacterium bovisincreases the sensitivity of mice to the lethal effect of LPS and results in an efficient priming for cytokine production. In response to low doses (1 γg/mouse) of LPS, BCG‐primed mice produce interleukin‐12 (IL‐12) which controls IFN‐γ production, as demonstrated by the ability of neutralizing anti‐IL‐12 antibodies to suppress IFN‐γ production. However, the concentration of the biologically active IL‐12 p70 heterodimer is similar in the serum of both BCG‐primed or unprimed mice, reaching levels of 1–3 ng/ml at 3–6 h after LPS injection, whereas IFN‐γ production was observed only in BCG‐primed mice. The priming effect of BCG on IFN‐γ production appears to be mostly due to its ability to increase TNF‐α production, which acts as cofactor with LPS‐induced IL‐12 in inducing IFN‐γ production, as shown by the ability of injection of TNF‐α and LPS (1 γg/mouse), but not LPS alone, to induce IFN‐γ production. However, in addition to TNF‐α, other LPS‐induced cofactor(s) are required in cooperation with IL‐12 to induce optimal IFN‐γ production, because co‐injection of TNF‐α and IL‐12, sufficient to induce serum concentrations of both cytokines higher and more persistent than those obtained by injection of LPS, was not sufficient to induce IFN‐γ productionin vivo. Neutralizing anti‐IL‐12 antibodies, in addition to inhibiting thein vivoLPS‐induced IFN‐γ production, also completely protect BCG‐primed mice injected with up to 10 μg of LPS from shock‐induced dea

ISSN:0014-2980    

DOI:10.1002/eji.1830250307

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractPrior studies in the human have implied an important function for CD10 (CALLA, neutral endopeptidase 24.11) in early lymphoid development. To examine the role of this ectoenzyme in an experimental system, a rat mAb specific for mouse CD10, termed R103, was generated. Immunohistological and flow cytometric analyses indicate that the distribution of CD10 in non‐lymphoid anatomical compartments is virtually identical in human and mouse. However, CD10 expression within the hematopoietic system is strikingly different. In contrast to human spleen, lymph node and thymus, the corresponding mouse organs contain no detectable CD10+cells. Mouse granulocytes, unlike human granulocytes, also lack CD10 expression. Five‐color flow cytometric studies of adult bone marrow (BM) from C57BL/6 and BALB/c mice with mAb specific for CD43, B220, HSA, BP‐1 and immunoglobulin M fail to detect any significant number of CD10+cells at pro‐B, pre‐B or B cell stages. In addition, lymphoid cells in both (rIL‐7) independent and rIL‐7‐dependentin vitropro‐B cell cultures lack CD10 expression. Consistent with this result, CD10 mRNA is not detected. Unlike the AA4.1+population from day 13 and 14 fetal liver, the CD10+subset is unable to reconstitute T and B lymphoid compartments in RAG‐2−/−mice. Nevertheless, mouse CD10 is readily found on BM stromal elements known to support early B lineage lymphoid development. Given the common expression of CD10 on human and mouse BM stromal elements, this enzyme may have an important function in the stromal cell‐depende

ISSN:0014-2980    

DOI:10.1002/eji.1830250308

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractInterferon‐γ (IFN‐γ) is a potent immune regulatory cytokine and is, in addition, involved in the induction of antiparasitic effector mechanisms in different cell types. The first step of IFN‐γ action is its binding to a specific receptor. Furthermore, it has been shown that IFN‐γ binds with a great affinity to the heparin‐like structure of heparan sulfate, which is localized in basement membranes and on cell surfaces. In this study, we analyze the effect of heparin and heparan sulfate on three different IFN‐γ‐mediated activities inducible in human glioblastoma cells (87HG31 and 86HG39).We find firstly that heparin is able to inhibit IFN‐γ‐mediated induction of major histocompatibility complex (MHC) class II antigen expression on 87HG31 cells, an effect which can be abrogated by protamine. Secondly, we show that heparin inhibits the IFN‐γ‐induced toxoplasmostasis within 86HG39 cells in a dose‐dependent fashion, and thirdly that heparin inhibits the IFN‐γ‐mediated induction of the tryptophan‐degrading enzyme indoleamine 2,3‐dioxygenase. In contrast to IFN‐γ‐induced effects, the activity of other cytokines, such as interleukin (IL)‐1, IL‐2 and IL‐6, is not influenced by heparin. The possible mechanism o

ISSN:0014-2980    

DOI:10.1002/eji.1830250309

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractUpon infection withLeishmania major, a cause of human cutaneous leishmaniasis, mice of resistant strains are able to control the infection, with lesions resolving spontaneously. A long‐lasting cell‐mediated immunity protects them from reinfection. Nevertheless, small numbers of viable parasites persist in the lymph nodes of these mice. We have recently documented that, in addition to macrophages, epidermal Langerhans cells can ingestL. major. Furthermore, Langerhans cells have the unique ability to transport viable parasites from the infected skin to the draining lymph node for presentation to antigen‐specific T cells and initiation of the cellular immune response. During migration, Langerhans cells develop into dendritic cells. In the present study, we analyzed whether dendritic cells support the persistence of parasites in immune hosts. Immunohistological studies and assaysin vitroshowed that in the lymph nodes of mice that have recovered from infection withL. major, both macrophages and dendritic cells harbor viable parasites. However, only dendritic cells were able to induce a vigorous T‐cell immune response toL. major in vitroin the absence of exogenous antigen. Tracking experiments conductedin vivosuggested that the infected dendritic cells in the lymph nodes are derived from Langerhans cells that have emigrated from the skin. The data demonstrate thatL. major‐infected dendritic cells and macrophages in lymph nodes of immune animals represent long‐term host cells, but only dendritic cells have the ability to present endogenous parasite antigen to T cells. Long‐term infected dendritic cells may thus allow the sustained stimulation of a population of parasite‐specific T cells, protecting the mice from reinfection. Our results favor the hypothesis that the persistence of antigen supports the maintenance of T cell memory and that dendritic cells are critically involved

ISSN:0014-2980    

DOI:10.1002/eji.1830250310

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractExtrachromosomal circular DNA purified from bone marrow cells of 2‐weeks‐old rabbits was assayed by polymerase chain reaction to determine the relative rearrangement frequencies of immunglobulin DHto JHgenesin vivo. DHgenes rearranged to individual JHgenes with different frequencies. This bias did not correlate with potential sequence overlaps in the DHor JHcoding sequences. The JH2 and JH4 genes were the preferred targets of recombination in primary rearrangements. Although primary rearrangements to JH6 were relatively infrequent, secondary rearrangements were detected. This assay also revealed previously undescribed JHpseudogenes with functional recombination signal sequences. Analyses of genomic VDJHindicated that B cells expressing VDJH4 heavy chains survived and dominated in the bone marrow environment due to secondary rearrangements and/or post‐rearrangement sele

ISSN:0014-2980    

DOI:10.1002/eji.1830250311

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY