The specificity of B lymphocytes activated in the acute phase of murine Trypanosoma cruzi infection was analysed in a panel of immunoglobulin-secreting hybridomas derived by fusion of lymph node cells 7 days after intraperitoneal parasite inoculation. The immunoglobulin isotype distribution of the hybrids reflected the total plaque-forming cell (PFC) response in the animal at this point, with a predominance of IgG2a, IgM, and IgG2b. Screening of the hybridoma antibodies on parasite antigens by three independent methods (western blot, ELISA, and immunofluorescence) revealed only one (out of a total of 51) that bound a parasite molecule with an apparent molecular mass of 180 kDa. In contrast, antibodies of both IgM and IgG classes were found to react with a panel of autologous antigens. These results establish that most B cells activated by T. cruzi infection are not specific for parasite antigens and therefore indicate the relevance of analysing the totality of host responses to infection.

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Sera of normal nonimmunized rabbits, pigs, calves, and humans contain tubulin-reactive antibodies. Usually, low amounts of antibodies against tubulin of the IgG class (2.5-4 mg/100 ml of serum from nonimmunized animals) were isolated. Anti-tubulin antibodies were also produced by injecting ig tubulin in complete Freund's adjuvant into rabbits. Slightly higher amounts of anti-tubulin antibody were isolated from sera of immunized rabbits (7 mg/1 00 ml of serum) The cytoplasmic network of microtubules of Tcc 36 mouse cells in culture was not clearly stained by natural anti-tubulin antibodies, but dense staining of the centrosphere was observed. In contrast, induced anti-tubulin antibodies densely stained cytoplasmic microtubular networks. Vinblastine-induced tubulin paracrystals were equally stained by natural and induced anti-tubulin antibodies.The occurrence of natural antibodies directed against various substances is known and has been reviewed by Boyden (1). The case of blood group antigens is particularly well established (2). Recently, natural autoantibodies directed against brain antigens common to several species (3) and against thymus cells (4) have been found in the sera of nonimmunized mice. Isolation of carbohydrate-specific immunoglobulin from the serum of healthy animals of various species, using insolubilized bovine fetuin, has also been recently reported (5). In this last study it was pointed out that the low amount of anti-carbohydrate antibodies which was found in the serum of nonimmunized animals did not significantly increase after immunization with the corresponding antigen. The above studies dealt with antigens whose main characteristics were their presence in many species of animals and their poor immunogenicity. Tubulin seems to belong to this class of antigen. Indeed, the primary structure of tubulin is apparently very similar in various species (6), and only low antibody titers are found in the sera of animals injected with this molecule (7). These antisera allowed a fine visualization of a cellular cytoplasmic network by indirect immunofluorescence (7-9). We have recently prepared antisera against tubulin in order to check the possible interaction of cell surface receptors with microtubules, a possibility that was suggested to us by our previous experiments (10). Testing Serum Source. Normal rabbit sera obtained from several nonimmunized apparently healthy animals were pooled. Normal human serum and umbilical cord serum were obtained from the Centre National de la Transfusion Sanguine (6, Rue Alexandre-Cabanel, 75015 Paris, France). The normal pig serum, the anti-lysozyme pig serum, and the calf serum were a gift from J. J. Metzger (Institut National de la Recherche Agronomique, Grignon, France). We used the serum of newborn piglets and 14-day-old germ-free piglets, obtained by hysterectomy. These were gifts from R. Ducluzeau (Institut National de la Recherche Agronomique, Jouy-en-Josas, France). Fetal calf serum was purchased from Gibco-Biocult, Scotland. Rabbit antiserum to tu...

The pathogenesis of gold-induced autoimmunity and membranous glomerulopathy is not well understood. HgCl2 and D-penicillamine, other chemicals known to trigger membranous glomerulopathy in humans, induce autoimmune manifestations in Brown-Norway (BN) rats but not in Lewis (LEW) rats. These chemicals trigger T-cell clones which are specific for self class II molecules from the major histocompatibility complex and are probably responsible for the polyclonal B-cell activation observed. The aim of this work was to test the effects of aurothiopropanolsulphonate (ATPS) in BN and LEW rats. In BN rats, ATPS induced a polyclonal B-cell activation marked by lymphoproliferation, hyperimmunoglobulinaemia affecting mainly IgE, and by the production of numerous autoantibodies. A glomerulonephritis occurred, initially due to anti-glomerular basement membrane antibody deposition, and later to the formation of granular deposits, occasionally resulting in a typical membranous glomerulopathy. Self class-II-specific T-cells were found that might be responsible for the polyclonal B-cell activation. Lewis rats were free of glomerulopathy but, like BN rats, exhibited an interstitial nephritis and some degree of polyclonal B-cell activation. These findings demonstrate that, depending on the strain, ATPS triggers different B-cell clones inducing different degrees of autoimmunity.

Six hundred and twelve monoclonal Ig (MIg) were studied for their antibody activity against the following autoantigens: actin, tubulin, thyroglobulin, myosin, myoglobin, fetuin, albumin, transferrin, and double-stranded DNA (dsDNA). Of these 612 MIg, 36 (i.e., 5.75%) were shown to possess antibody activity. Thirty-two of these 36 (5.22% of the total) were mainly directed against actin. The four others were directed, respectively, against tubulin, myosin, thyroglobulin, and dsDNA. The interaction of the MIg with the respective antigen was demonstrated by immunoenzymatic methods with monospecific antisera and by blotting experiments. Furthermore, this interaction in the 12 cases studied was mediated by the dimeric fragment F(ab')2 of the MIg. The MIg with antitubulin, antithyroglobulin, and anti-dsDNA activities were exclusively inhibited by their homologous antigens. Those with antiactin activity were predominantly inhibited by actin and also by tubulin and thyroglobulin. The one binding to myosin was, for the most part, inhibited by myosin and also significantly by actin and tubulin. Retrospective clinical analysis was possible for 31/36 patients. Twenty- six of 31 had malignant lymphoplasmocytic disorders. The five others were followed for miscellaneous disorders without overt signs of multiple myeloma (MM) or Waldenstrom's macroglobulinemia (WM). The correlation between the antibody activity of the MIg and the clinical features is discussed. These results indicate that a high proportion of MIg possess antibody activity against actin (5.22%). This incidence contrasts sharply with the positive reactions found toward all the other antigens tested: only one each for dsDNA, tubulin, thyroglobulin, and myosin, and none against myoglobin, fetuin, albumin, and transferrin. The significance of these results and the relationship between MIg and natural antibodies are discussed.