摘要:

AbstractA monoclonal antibody, FR51, raised against the IgG Fc receptor (FcγR) of the human monoblast cell line U937 was used to analyze the distribution of this antigen on various human cells. This antibody inhibited the binding of human IgG to the FcγR on U937 cells, HL‐60 cells and human peripheral blood monocytes. In contrast, the FcγR on human granulocytes (neutrophil cells) and on an Epstein‐Barr virustransformed human lymphoblastoid cell line (Raji) were not recognized, indicated by the failure of blocking the binding of human IgG ligand to the FcγR on these cells. By affinity chromatography of detergent‐containing cell free lysates of surface‐iodinated U937 cells, HL‐60 cells and monocytes, a protein of 70‐kDa was isolated. This protein was identified as the FcγR by rebinding the isolated protein to immobilized human IgG. Removal of the carbohydrate moiety with endo‐ß‐N‐acetylglucosaminidase F demonstrated that the receptors consist of a 40‐kDa polypeptide. Analysis of the polypeptide patterns obtained by proteolytic digestion of either mature (70‐kDa) or deglycosylated (40‐kDa) receptors isolated from monocytes, U937 cells and HL‐60 cells strongly suggests that the FcγR are identical. The monoclonal antibody FR51 specifically reacts with FcγR on human monocytes, a myeloblast and a monoblast cell line but not with the receptors on a

ISSN:0014-2980    

DOI:10.1002/eji.1830170502

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractA lymphokine demonstrating human B cell differentiation factor (BCDF)‐like activity was isolated from immature (MOLT‐4f, CCRF‐CEM and CCRF‐HSDB‐2) and mature (HUT‐78) malignant human T lymphoid cell lines and from human B lymphoblastoid cell lines (BJAB and ALL‐7031‐B). All the cell lines were grown long term in serum‐free medium. This BCDF‐like activity has a molecular mass in the range of 40–60 kDa and stimulates immunoglobulin synthesis of cell lines capable of producing IgA (GM‐1056), IgG (GM‐1500 and CESS) and IgM (CBL#3). It was not produced by a myeloid cell line. We were only able to identify the differentiation activity produced by the T and B cell lines by using appropriate molecular mass fractions from the serum‐free medium as controls. This BCDF‐like activity is different from that of the human BCDF so far described as it has a higher molecular mass and is constitutively produced by malignant T lymphoid cell lines which are human T cell leukemia virus‐I negative and

ISSN:0014-2980    

DOI:10.1002/eji.1830170503

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe primary infection byP. chabaudiinduces an increase of the numbers of splenic immunoglobulin (Ig)‐secreting B cells in both athymic and euthymic BALB/c mice. The isotypic pattern of the polyclonal response is restricted only in euthymic mice where IgG2a, IgG2band IgM plaque‐forming cells (PFC) predominate. In immunized animals, protected against a parasite challenge, the isotypic pattern of splenic PFC is completely different, the IgG1and IgM isotypes constituting the main part of the response. Reinoculation of immune‐protected animals induces a PFC response which is dose dependent and accentuates the characteristic isotypic profile of the immune‐protect

ISSN:0014-2980    

DOI:10.1002/eji.1830170504

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractIn vivo, subclones derived from EL4 lymphoma cells generate suppressor T lymphocytes specific for anti‐EL4 immune responses. Spleen cells of EL4‐sensitized C57BL/6 mice down‐regulate thein vitroinduction of EL4‐specific cytolytic T lymphocytes (CTL). In addition, EL4‐sensitized spleen cells interfere with the antigen response of two T lymphocyte clones. These recognize, in an H‐2bcontext, a self‐antigen on spleen cells that is also expressed by transformed cells, including EL4. The simultaneous anti‐self and anti‐EL4 specificity of the helper and suppressor activities suggests, therefore, that they are the product of anin vivoautoimmune reaction to EL4. The anti‐self suppression might aim to re‐establish self‐tolerance, at the same time down‐regulating responses against immunogenic epitopes that are co‐expressed with the self‐antigen on the EL4 cells. This agrees well with our observation that suppressor T cells, apparently elicited by suppressogenic epitopes on non‐immunogenic EL4 subclones, down‐regulate the CTL response elicited by immunogenic EL4 subclones. The additional self‐specificity of this suppression indicates that the suppressogenic epitopes at least

ISSN:0014-2980    

DOI:10.1002/eji.1830170505

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThis study describes the localization of the previously purified T cell‐specific serine proteinase, termed TSP‐1 (M. M. Simon et al.,EMBO J.1986.5:3267), within cytoplasmic granules of cytolytic T cell lines (CTLL). Subcellular fractionation of disintegrated CTLL (ruptured by nitrogen cavitation) was accomplished by Percoll density gradient centrifugation of cell lysates (postnuclear supernatant). Individual fractions were tested for proteinase activity on chromogenic peptide substrates and for the presence of TSP‐1 by Western blot analysis. In addition, each fraction was assayed for cytolytic activity against sheep red blood cells (SRBC), for protein and for additional marker enzymes to assess the enrichment for cellular organells. All serine enzyme‐type molecules including TSP‐1 expressed by CTLL were identified by labeling cell lysates or gradient fractions with the serine proteinase‐specific affinity ligand tritiated diisopropyl fluorophosphate ([3H]DFP) in the presence or in the absence of class‐specific or enzyme‐specific proteinase inhibitors and subsequent sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. The data demonstrate that the Percoll gradient fraction, which was shown by morphological examination in the electron microscope to be highly enriched for cytoplasmic granules, also contained>80% of proteinase activity in addition to the granule‐associated structures cytolysin and aryl‐sulfatase. The identity of the granule‐associated proteinase in two independent cell lines, CTLL HY3‐Ag3 and CTLL 1.D.9, with the serine proteinase TSP‐1 is indicated by (a) its specificity for the chromogenic substrate H‐D‐Pro‐Phe‐Arg‐p‐nitroanilide, (b) its sensitivity to class‐specific as well as TSP‐1‐specific enzyme inhibitors and (c) by its reactivity with a polyvalent TSP‐1‐specific rabbit antiserum. Both CTLL contain a [3H]DFP‐labeled protein that migrates with a molecular mass of 60 kDa under nonreducing conditions and with 30 kDa under reducing conditions and which can be inactivated by the TSP‐1‐specific inhibitor H‐D‐Pro‐Phe‐Arg‐chloromethylketone. CTLL HY3‐Ag3 (a long‐term culture CTLL with natural killer‐like activity) but not CTLL 1.D.9 (an antigen‐specific short‐term cultured CTLL) express in addition a further [3H]DFP‐binding protein which migrates with 27 kDa under nonreducing or reducing conditions. No substrate specificity was found for this molecule. The pos

ISSN:0014-2980    

DOI:10.1002/eji.1830170506

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe induction of class I HLA expression by interferon‐α (IFN‐α) was studied in lymphoid cells arrested or traversing different stages of the cell cycle. Exponential cultures of MOLT‐4 cells and the MOLT‐4 cell variant YHHH were treated with the cell cycle inhibitors aphidicolin and colcemid to obtain cell populations arrested in G1/S and G2/M, respectively, and also cells traversing from S to M andvice versa.Cytofluorimetry with the monoclonal antibody YTH/76.3 (which specifically detects those class I molecules which are most susceptible to IFN‐α induction) was used to quantitate the class I HLA response to IFN‐α. The results showed that the response to IFN‐α is not restricted to a given stage of the cell cycle. These studies also revealed that when the cells were arrested at G1/S, the absolute level of class I HLA expression was enhanced 2–3‐fold, both in the presence or absence of either IFN‐α or IFN‐γ. Therefore, even when absolute levels changed, the ratio of IFN‐induced expression to basal expression remained constant at all cell cycle stages. The level of expression of another surface antigen (the CD1 antigen HTA‐1) was not affected by the G1/S block. The results were confirmed by dot blot hybridization of poly (A)+RNA using cDNA‐specific probes. These findings suggest that the effect of IFN‐α is continuous throughout the cell cycle but that a G1‐dependent event determines the extent of class I HLA expression, and leads to a synergistic super

ISSN:0014-2980    

DOI:10.1002/eji.1830170507

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractUpon incubation at 37°C with purified human C3b (500 μg/ml), polymorphonuclear neutrophils (PMN) were found to express up to 50% more C3b receptors (CR1) than PMN incubated with buffer alone. This up‐regulation of CR1, assessed by the binding of radiolabeled CR1‐specific monoclonal antibody, was dependent on the dose of C3b, occurred within 10–20 min and was stable for at least 90 min. PMN incubated with C3b also demonstrated enhanced CR1‐dependent binding functions, such as EC3b rosette formation and phagocytosis of EIgGC3b particles. C3b at a concentration of 500 μg/ml induced up to 90% increase in the attachment or the phagocytic index. However, CR1 remained unable to promote phagocytosis of EC3b intermediates. Fc receptor‐mediated functions were unaffected by the treatment with C3b. The active factor was characterized as monomeric C3b and, in particular, shown to be distinct from C5a. C3b purified by anion‐exchange fast protein liquid chromatography on a Mono Q column or eluted from a monoclonal anti‐C3b‐Sepharose retained its modulating activity, while native C3 or C3 fragments such as iC3b, C3c or C3d,

ISSN:0014-2980    

DOI:10.1002/eji.1830170508

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractPrevious studies from this laboratory have shown thatMycoplasma hyorhinisinteracts with some unoccupied, high‐affinity 45‐kDa receptors for IgE on rat basophilic leukemia (RBL) cells to induce the formation of 71‐kDa receptors for IgE. The present study demonstrates that when IgE is bound to the high‐affinity receptors, exposure of RBL cells to mycoplasma leads to a time‐dependent degradation of the cell‐bound IgE into fragments of 186 kDa, 158 kDa and 115 kDa, all of which remain bound to the receptors. Upon reduction, these fragments yield 67‐kDa and 55‐kDa ϵ chain‐derived polypeptides. The degradation appears to start at the N‐terminus of the IgE, leading eventually to a complete loss of L chains. In the absence of mycoplasma, the IgE remains relatively intact throughout the same time period with a molecular mass of 210 kDa. The observed degradation of receptor‐bound IgE by mycoplasma, should it also occurin vivo, could have important consequences as far as the IgE‐dependent media

ISSN:0014-2980    

DOI:10.1002/eji.1830170509

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractWe studied the activation of small resting mouse T lymphocytes by antibodies to the T cell antigen receptor in combination with antibodies to other T cell surface antigens. Solid‐phase but not soluble antibodies KJ16‐133 and F23.1, both directed to β chains of the Vβ8 family, activate T cells to proliferate in the presence of growth factors, in a dose‐dependent fashion. Antibodies to Lyt‐2 and to L3T4 had no activating effect at any concentration. However, submitogenic concentrations of KJ16‐133 and of F23.1 synergized with a wide range of concentrations of anti‐Lyt‐2 and anti‐L3T4 to cause T cell proliferation similar or greater in magnitude to that caused by high concentrations of anti‐T cell receptor antibody. Synergistic activation was also observed with antibodies to Lyt‐1, LFA‐1 and H‐2 class I antigens but to a significantly lower degree. This was particularly clear in limiting dilution experiments in which the corrected frequencies of T cells proliferating in response to low amounts of anti‐T cell receptor antibody together with anti‐Lyt‐2 were 1/4 to 1/7 for BALB/c T cells. The frequencies of BALB/c T cells responding to high concentrations of anti‐T cell receptor antibody alone were between 1/14 and 1/126 and still lower frequencies of T cells proliferated in synergistic responses with anti‐LFA‐1 or anti‐Lyt‐1. Synergistic activation leads to the induction of functional cytotoxic cells. We interpret these data as suggestive that cross‐linking of the T cell antigen receptor with either Lyt‐2 (CD8) or L3T4 (CD4) represents an optimal activating signal for resting T cells. We think that, in physiological T cell activation, cross‐linking of the T cell receptor to CD8 or CD4 is induced by their simultaneous binding to major histocompatibility complex (MHC) class I (for CD8) or MHC class II (for CD4) molecules on stimulator cells. We consider the possibility that similar cross‐linking requirements may also exist during T cell repertoire selection in ontogeny, thus accounting for the strict coexpression of MHC class I and class II‐restricted T cell

ISSN:0014-2980    

DOI:10.1002/eji.1830170510

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe antigen fine specificity of T cell hybridomas recognizing the horse apocytochromecfragment 1–65, restricted to the I‐Abmolecule, was determined to gain some insight into the molecular nature of T cell antigenic peptides. Two major groups of clones specific for distinct subsites, namely residues 1–38 and 39–65, could be identified. Hybridomas recognizing the latter determinant were further tested with different horse cytochromecpeptides and analogues. This analysis revealed the presence of at least two epitopes encompassed by residues 47–53 and 48–53. Furthermore, clones specific for the amino acid sequence 48–53 showed considerable heterogeneity in respect to the antigen concentration required to obtain 50% of the maximal interleukin 2 secretion. Most prominent was the heteroclitic response towards tuna cytochromecwhich differs at positions 44, 46 and 47 from the horse cytochromecmolecule in the relevant region. Comparison of the conformation of the sequence 43–46 between the two cytochromecsuggests that this segment, which forms a 310bend, may be important in maintaining the proper structure of the antigenic determinant. Moreover, the variations up to 180‐fold in the concentrations of the cross‐reacting cytochromecand peptides required for stimulation were not always correlated with the maximal interleukin 2 secretion they induced. This indicates that the biological response, that is supposed to be an indication of the affinity of the T cell receptor for its ligand, is not necessarily a function of the an

ISSN:0014-2980    

DOI:10.1002/eji.1830170511

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY