Deficient production of anti-red cell autoantibodies by mice with an X-linked B lymphocyte defect

The influence of adjuvants on the generation of autoantibody and specific suppression in rat erythrocyte-immunized mice

A number of adjuvants were investigated for their ability to modulate either the autoimmune response induced in mice by immunization with rat erythrocytes (RRBC) or the ability of RRBC-primed spleen cells to suppress the induction of anti-red cell autoimmunity in recipient mice. The inability of the agents used to do so is discussed on the background of models used to explain the generation of suppression in this system.

Comparative analysis of natural antibody specificities among hybridomas originating from spleen and peritoneal cavity of adult NZB and BALB/c mice

A preliminary experiment showed that the supernatants of in vitro cultured peritoneal cells (rich in Ly-1 B cell subset shown to secrete most IgM autoantibodies against bromelain-treated mouse red blood cells (BrMRBC) and DNA) from different mouse strains did not contain any significant antibody activity against DNA and cytoskeleton proteins, although the presence of anti-BrMRBC antibodies was clearly evident. Therefore, we investigated comparative natural antibody (NAb) specificities against an antigen panel (DNA, cytoskeleton proteins, IgG, bovine serum albumin (BSA), BrMRBC, trinitrophenyl (TNP), and trimethylammonium (TMA) haptens) among Ig-secreting hybridoma collections from the splenic (158) and peritoneal (230) immune compartments of autoimmune New Zealand black (NZB) and lipopolysaccharide (LPS)-stimulated BALB/c mice. The data showed: (i) isotypic restriction (mu and gamma 3 only), predominance of TMA ion-reactive (including BrMRBC) but negligible anti-DNA-reactive antibody specificities, and lack of simultaneous polyspecific widespread reactivity (i.e. at least four or more antigens) against DNA and cytoskeleton proteins in the peritoneal cavity; (ii) predominance of simultaneous widespread polyspecific reactivity against DNA and cytoskeleton proteins but negligible or no TMA hapten-reactive antibody specificities in the spleen. These observations reflect certain differences in the B cell repertoire of peritoneal cavity (rich in Ly-1 B cells) compared with spleen. The NAb against BrMRBC and those reactive with DNA and cytoskeleton proteins, which have been suggested to be secreted by the Ly-1 B cell subset, are distinguishable on the basis of the presence of separate recurrent idiotypes and preferential localization of B lymphocytes directed against these autoantigens.

Autoantibodies against bromelainized mouse erythrocyte: strain distribution of serum idiotype expression and relative peritoneal cell activity

Previously, we demonstrated that the naturally occurring mouse autoantibodies directed against bromelainized mouse red blood cells (BrMRBC) comprised a family of structurally related molecules bearing a common idiotypic determinant (CP) based on structural and idiotypic analysis of a series of anti-BrMRBC monoclonal autoantibodies derived from a fusion of peritoneal cells (PerC) with plasmacytomas. In the present studies, we have evaluated the quantitative expression of circulating CP idiotype related to autoantibodies against BrMRBC in relation to specific PerC anti-BrMRBC plaque-forming activity in an individual mouse of different strains. The data presented here show no direct relationship between serum CP idiotype expression and PerC anti-BrMRBC plaque-forming activity in an individual mouse of all strains tested. However, the circulating CP idiotype content is higher in strains, viz., CBA/J, NZB, C3H, BXSB, and Biozzi high responder (H) mice which exhibit a high perC autoantibody secretory activity against BrMRBC. The strains such as BALB/c, DBA2, SJL/J, CBA/N, and Biozzi low responder (L) express little or no circulating CP idiotype with a corresponding small or no PerC anti-BrMRBC activity. Furthermore, the PerC "auto"-immune phenomenon is markedly expressed in the normal CBA/J strain since these mice show a higher percentage ratio of CP idiotype over serum IgM (2.68%) as well as highest PerC anti-BrMRBC plaque-forming activity (11,319 +/- 18,029 plaques per million viable cells) compared to other normal and autoimmune strains tested. Nevertheless, the highest circulating serum CP idiotype (49.4 micrograms/ml) is observed in the autoimmune NZB mouse. The immunodeficient CBA/N mice fail to express detectable levels of CP idiotype in their serum. The experiments conducted in genetically selected outbred Biozzi (H and L) strain have revealed remarkable differences in serum CP idiotype expression as well as PerC anti-BrMRBC plaque-forming activity in these two lines. The expression of mouse PerC "auto"-immune phenomenon and quantitative circulation of CP idiotype in the serum seem to be related to regulatory mechanisms as for sheep erythrocytes and other natural antigens earlier demonstrated to be under polygenic regulation in Biozzi (H and L) mice.

Carrier-specific induction of suppressor cells controlling anti-erythrocyte autoantibody production in mice

Mice immunized with rat erythrocytes develop anti-erythrocyte autoantibodies, distinct anti-rat erythrocyte agglutinins, and suppressor-inducer cells, which regulate the production of autoantibody but not anti-rat erythrocyte agglutinins upon transfer to naive recipients. In this report, we have tried to determine the specificity of the suppressor-inducer cells. CBA/N mice (which express an X-linked genetic B-lymphocyte defect) immunized with rat erythrocytes developed no autoantibodies but normal levels of anti-rat erythrocyte antibodies and suppressor-inducer cells, thereby suggesting that neither idiotypes on autoreactive B cells nor idiotypes on autoantibody itself, stimulate suppressor-inducer cells. In contrast, rat erythrocyte-primed spleen cells suppressed both a primary 2,4,6 trinitrophenyl (TNP) response and anti-erythrocyte autoantibody production (but not anti-rat erythrocyte antibodies) upon transfer to naive recipients and challenge with TNP-rat erythrocytes. It is considered that the suppressor-inducer cells are carrier-specific and that they are not stimulated by idiotypes on either autoantibody or autoreactive B cells.

Polyclonal B-cell response to stimulation with Escherichia coli lipopolysaccharide in dietary protein restriction

The polyclonal B-cell response to Escherichia coli lipopolysaccharide was studied in C57BL/6 mice maintained after weaning on either a moderate protein-restricted diet with 8% casein or a normal diet. After in vitro or in vivo stimulation with the endotoxin, autoreactive and anti-hapten antibody-producing cells were quantitated by direct plaque assay, using bromelain-treated mouse erythrocytes and trinitrophenylated sheep erythrocytes as targets. Larger numbers of plaque-forming cells were generated in cultures of spleen cells from dietary-restricted than from normal mice stimulated with various doses of lipopolysaccharide. The number of background plaque-forming cells was also higher in nonstimulated spleen cell cultures from restricted animals. After injection of lipopolysaccharide in vivo, the number of cells producing antibodies to bromelain-treated mouse erythrocytes per 10(7) spleen cells was significantly increased in dietary-deficient mice. The results are discussed in relation to the different sensitivities of lymphocyte populations to protein deficiency and to the possible presence of high levels of endogenous polyclonal B-cell activators in the restricted mice.

Antibody mediated regulation of immune responses. I. Enhancement of specific antibody responses through IgM antibodies

Injection of monoclonal IgM antibodies to sheep red blood cells (SRBC) 2 h before immunization with a low dose of antigen (Ag) specifically enhances the direct and indirect plaque-forming cell response. This enhancement was specific: the specific antigen had to be present; the plaque-forming cell (PFC) response to TNP-Ficoll- or bromelein-treated mouse red blood cells was not enhanced; the PFC response to SRBC was not enhanced by injections of monoclonal antibody to TNP. The optimum conditions for enhancement were found to be dependent on both the dose and the time of administration of antibody in relation to antigen. The possible mechanisms for this enhanced antibody response are discussed.

Non-specific immune responses in CBA/N mice infected with Trypanosoma brucei

CBA/N mice carry a genetic defect which causes a maturational arrest of normal B lymphocyte development, and results in an inability to mount IgM antibody responses against certain T lymphocyte-independent antigens. These mice were found to survive an experimental infection with Trypanosoma brucei two to three times longer than conventional mice. This enhanced survival does not appear to be related to the level of infection of the host since parasitaemias were similar in all strains tested. In addition, the level of non-specific polyclonal B cell activation as assessed by the enumeration of anti-TNP antibody-producing cells in the spleens of infected animals was found to be similar in CBA/N, CBA/CaT6 and A/J mice. In contrast, the level of circulating immune complex-like material was lower in CBA/N mice at a time when mice of other strains were dying from the effects of the infection. Finally, although CBA/N mice survive a T. brucei infection for a longer time interval, they exhibit a non-specific immunosuppression similar to that seen in conventional mice.