摘要:

AbstractPurified IgG from a rabbit anti‐mouse brain antiserum (RaMB), previously shown to activate most Lyt‐2+T cells, was probed for lectin‐like effects on cell‐mediated cytolysis (CML) and found to induce “nonspecific” killing of syngeneic B cell targets by allospecific cytotoxic T lymphocytes (CTL) as effectively as concanavalin A, and at levels comparable to antigen‐specific cytolysis of target cells. Interestingly, RaMB‐mediated “nonspecific” CML of syngeneic targets, by polyclonally or specifically activated CTL, was restricted to B cell targets and cold target inhibition experiments indicated that syngeneic target cell blasts do not functionally interact with effector CTL in the presence of RaMB. The role of target cell Fc receptors was demonstrated by the competitive inhibition of RaMB‐dependent CML by normal rabbit IgG. We conclude that RaMB both activates and bridges the effector CTL to target cells, RaMB‐mediated “nonspecific” CML being a similar phenomenon to lectin‐facilitated “nonspecific” cytolysis, and the mirror image of classical ADCC.These observations allowed us to interprete the effects of RaMB on allo‐major histocompatibility complex‐specific CML. Since RaMB stimulates specific CML of B cell targets while selectively blocking that of T cell targets, we conclude that RaMB antibodies interact with structures associated with the CTL antigen receptor, explaining the contradictory effects previously reported with monoclonal antibodies against the CTL receptor complex, which can both s

ISSN:0014-2980    

DOI:10.1002/eji.1830151002

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractIt is a common observation that there is variability in the rate of activation of C1, the first component of complement, when bound to immune complexes. The cause of this variation has been investigated with experiments designed to assess separately the effect of antibody, antigen and C1 density. Using125I‐labeled C1 and a rat monoclonal antibody specific for the class I antigen, it has been found that the rate of activation is primarily dependent on antibody density on the cell surface and not on antigen or C1 density. This finding supports the suggestion that direct contact between the Clr2Cls2subcomponent of C1 and antibody may be required for potentiation of C1 activatio

ISSN:0014-2980    

DOI:10.1002/eji.1830151003

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractWe describe a cytotoxic T lymphocyte‐mediated cytotoxicity assay in which the release of a cytoplasmic enzyme, adenosine deaminase (ADA), instead of the widely used radioactive chromium is a measure of target lysis. In this enzyme‐release assay the target is a mastocytoma P815‐derived cell line, noted P815 ADA++, isolated by applying a selection procedure devised to specifically amplify the ADA gene. Gene amplification in P815 ADA++was indeed demonstrated. Routine measurement of ADA activity from numerous supernatants is performed using a specific and sensitive colorimetric assay. The use of 96‐well microtiter plates as well as of an automatic Multiscan spectrophotometer makes this measurement rapid and convenient.We show that this ADA‐release assay is significantly more sensitive than the classical chromium‐release test because of its consistently lower (5 to 10‐fold) spontaneous release in 4 h, short‐term cytotoxicity experiments. We also found that it is especially suited for the rapid detection, by visual screening, of rare, active killer clones among large, heterogeneous cytotoxic T lymphocyte populations.The assay could easily be adapted to other tumor targets (EL4, YAC‐1, K562) of common use in studies involving immune lysis; indeed, the procedure of amplifying the ADA gene used in the isolation of the P815 ADA++hyperactive line may be generally applied

ISSN:0014-2980    

DOI:10.1002/eji.1830151004

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractThe human monocyte line, U‐937, derived from an individual with histiocytic lymphoma was studied for the expression of surface C3 receptors, after cultivation in the presence of phorbol myristate acetate (PMA) or T lymphocyte‐conditioned medium. Receptors were detected by using EAC4b, EAC3b, EC3b, EAC3bi and EAC3d intermediates. U‐937 cells, in exponential growth phase, poorly bound the intermediates; after exposure to PMA or T lymphocyte‐conditioned medium, U‐937 cells strongly bound both EAC3b and EAC3bi since about 50% of cells rosetted with these intermediates. This binding was totally inhibited by EDTA and by Mac‐1 monoclonal antibody, suggesting the presence of only CR3 receptor types on these cells. Although U‐937 cells formed rosettes with EACSb, there was no evidence for the presence of CR1 receptors since no rosette was observed either with EAC4b or with EC3b intermediates (EC3b were prepared by coupling purified C3b to erythrocytes with N‐succinimidyl 3‐(2‐pyridyldithio)propionate. As small amounts of factor H were present on EAC3b intermediates, incubation of EAC3b with U‐937 cells induced their transformation into EAC3bi and their binding to CR3. Moreover, U‐937 cells did not promote the cleavage of C3b in the presence of factor I alone, suggesting that these cells did not bear a sufficient amount of functionally active CR1. These results demonstrated that U‐937 cells predominantly expressed CR3. The study of the kinetics of EAC3bi rosette formation demonstrated that CR3 expression is closely related to PMA activation. We suggest that CR3 activity could result from a phosphorylat

ISSN:0014-2980    

DOI:10.1002/eji.1830151005

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractSera from patients with systemic autoimmune diseases often contain antibodies against small nuclear ribonucleoprotein (snRNP) particles. Anti‐Sm antibodies react with the entire set of U1, U2, U4, U5 and U6 (Ul‐U6) RNP particles whereas anti‐(U1)RNP sera specifically recognize particles containing U1 RNA. Here we performed semi‐quantitative immunoblotting using 16 human anti‐Sm, 15 human anti‐(U1)RNP sera and two mouse monoclonal antibodies to establish which snRNA‐associated proteins carry antigenic determinants. Almost every (15/16) human anti‐Sm sera recognized epitopes present on a 28‐kDa (B/B') protein doublet and on a 16‐kDa (D) polypeptide. Nine anti‐(U1)RNP sera also recognized the B/B' doublet, but in all cases a much stronger reaction was observed with one or more of the specifically U1 RNA‐associated 70 kDa, A or C antigens. With affinity‐purified antibody fractions eluted from individual antigen bands on nitrocellulose blots it is shown that the anti‐Sm‐reactive polypeptides B/B' and D contain common epitopes. We also report the finding of one human anti‐Sm serum with exclusive specificity for the B/B' doublet and a mouse monoclonal anti‐Sm antibody recognizing only the D protein, indicating that these antigens also carry unique epitopes. In immunoprecipitation assays, purified anti‐B/B' and ‐D antibodies react with (Ul‐U6) RNP while purified anti‐70 kDa, anti‐A and anti‐C antibodies precipitate exclusively U1 RNP particles. Finally, we established the subcellular localization of Sm and U1 RNP antigens using a biochemical cell fractionation procedure. Part of the 70 kDa and BIB' antigens were found in a nuclease and high salt‐resistant nuclear substructure, usually referred to as nuclear matrix, while the A and D antigens could be extracted completely from HeLa nuclei by ribonucleas

ISSN:0014-2980    

DOI:10.1002/eji.1830151006

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractThe efficiency of a number of B cell‐depletion techniques was examined in a functional assay. CBA (Iga) mice were primed with rat erythrocytes and their spleen cells transferred, before and after B cell depletion, to mice of the allotype‐congenic strain Igb. The recipients were challenged with rat erythrocytes and their anti‐erythrocyte autoantibody response was measured together with the donor (Iga) and host (Igb) anti‐rat erythrocyte antibody levels. Transferred unseparated cells suppressed erythrocyte autoantibodies and produced high levels of anti‐rat erythrocyte antibodies. Transfer of panned, rosetted or nylon wool‐passaged cells neither altered donor anti‐rat erythrocyte antibody levels nor abrogated suppression. By contrast, passage of rat erythrocyte‐primed B cells over Ig‐anti‐Ig‐coated beads resulted in removal of donor rat‐primed B cell activity and loss of suppressor cells. The B cell‐depletion techniques were effective at removing B cells as judged by the reduced number of fluoresceinated anti‐Ig‐labeled cells among unbound cells although analysis on a fluorescein‐activated cell sorter revealed that the most effective method was depletion on Ig‐anti‐Ig‐coated beads.B cell depletion by panning removed the capacity of virgin but not primed cells to make adoptive antibody responses after transfer suggesting that the primed cells most efficient in adoptive transfer have a lower density of surface Ig than virgin cells. Treatment of donors with drugs which abrogated transferrable suppression of erythrocyte autoantibodies did not alter donor anti‐rat erythrocyte antibody levels in recipients. It is considered that rat primed B cells are involved in the suppression of erythrocyte autoantibodies by acting as selective antigen‐presenting cells for T suppressor inducer cells, rather than through an anti‐

ISSN:0014-2980    

DOI:10.1002/eji.1830151007

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractThe numbers of cells and background plaque‐forming cells (PFC) in the spleen of C3H/HeJ mice increase exponentially during the first 2 weeks after birth, but much slower in bone marrow (BM). IgGland IgG2aPFC are the first non‐IgM PFC detectable, while IgG3and IgA PFC appear only around weaning. Adult‐type PFC numbers and isotype pattern are present in spleen and BM at 4 and 15 weeks, respectively. Neonatal splenic C3H/Tif B cells produce non‐IgM Ig classesin vitroin response to polyclonal activation by lipopolysaccharide or by helper T cells. These responses are of low magnitude during the first 2 weeks of life, but both secreted and membrane‐bound IgG1and IgG3isotypes are detectable already a few days after birth, in a pattern that is identical to that typical of T cell‐dependent or independent responses of adult cells. These results indicate full maturity of B cells in “switch” abilities already from birth, in spite of a general deficiency in terminal maturation. In addition, they demonstrate the complexity of isotype regulation in “background” antibod

ISSN:0014-2980    

DOI:10.1002/eji.1830151008

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractInterleukin 1 (ILI), but not IL2‐induced thymocyte proliferation was augmented by monoclonal antibodies (mAb) against the Ly 1 antigen. The anti‐Ly 1 mAb could also co‐stimulate thymocytes with phytohemagglutinin (PHA) alone, mimicking the effect of IL1. Moreover, overnight culture with PHA of thymocytes, but not of spleen T lymphocytes led to selectively enhanced expression of the Ly l antigen on the cell surface. Similar data were generated at the clonal level. Thus, a thymocyte hybridoma (22A6) could be stimulated to release IL2 in response to PHA plus IL 1, but also to PHA plus anti‐Ly 1 mAb. In addition, 22A6 exhibited enhanced cell surface expression of the Ly l antigen after overnight culture with PHA. These data suggest a critical role for the Ly1 antigen in thymocyte proliferation, perhaps by serving as an IL 1

ISSN:0014-2980    

DOI:10.1002/eji.1830151009

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractInduction of an allogeneic cytotoxic T lymphocyte (CTL) response is dependent, in part, on uptake and processing of the class I alloantigen by antigen‐presenting cells and subsequent Ia‐restricted recognition of the alloantigen by helper T cells, resulting in lymphokine production. The nature of the antigen‐processing event has been investigated using reconstituted membranes to replace the antigen‐presenting cells in the generation of a secondary allogeneic CTL response. Membranes were isolated from an Iad‐positive antigen presenting B cell lymphoma (D2N), detergent solubilized and then reconstituted together with affinity‐purified H‐2Kkantigen in the presence of protease inhibitors. These reconstituted vesicles, containing both syngeneic Ia and alloantigen, were able to induce the helper T cell arm of the CTL response in cultures depleted of antigen‐presenting cells. A variety of control experiments provided strong evidence that the helper T cells recognized the H‐2Kk, probably in its native form, in an Ia‐restricted manner on the vesicles, while the pre‐CTL can directly recognize H‐2Kk. Recognition was only effective if both the Ia and alloantigen were inserted into the same membrane bilayer. The results strongly suggest that the obligatory antigen processing event required for helper T cell recognition of alloantigen is simply the insertion of the alloantigen into the same membrane bilayer as the syngeneic

ISSN:0014-2980    

DOI:10.1002/eji.1830151010

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY

摘要:

AbstractThe role of T cell differentiation antigens in antigen‐specific and nonspecific cytotoxicity by human cytotoxic T lymphocyte (CTL) clones was investigated. In contrast to other reports, several monoclonal antibodies (mAb) against the T3 antigen only marginally blocked antigen‐specific cytotoxicity at high concentrations but induced cytotoxicity against third party cells at concentrations from 10 to 0.001 μg/ml. Susceptibility to anti‐T3‐induced lysis was variable but was found with all target cells, Incubation of CTL with anti‐T3 mAb even led to self‐destruction of the CTL. The effect was independent of the presence of Fc receptors on the target cell and could be obtained with F(ab')2fragments of the antibody as well. Only activated but not resting T cells could be induced to lyse by anti‐T3. Furthermore, this type of bystander killing of target cells could also be induced by the Ca2+ionophore A23187. Antibodies against the T8 differentiation antigen inhibited antigen‐specific, oxidation‐induced and antGT3‐induced cytotoxicity by T8+CTL clones, whereas triggering by the ionophore A23187 was not inhibited. These results show that undirected killing can be triggered in CTL by activating a transducing molecule directly without involving the antigen receptor. Since this triggering of the lethal hit can still be inhibited by mAb against the T8 molecule, the T8 molecule probably has a regulatory role in a late pha

ISSN:0014-2980    

DOI:10.1002/eji.1830151011

出版商:WILEY‐VCH Verlag GmbH    

年代:1985

数据来源: WILEY