Immune response deficiency of BSVS mice: I. Identification of Ir gene differences between A/J and BSVS mice in the antistreptococcal group A carbohydrate response

Ir gene-controlled response to haptenated hen ovomucoid: isotypic specificity and dominant nonresponsiveness

We have examined the isotypic pattern of the response of mice to the Ir gene-controlled antigen, dinitrophenyl-ovomucoid (DNP-OM). H-2 kappa mice are high responders (HR); (H-2b,d mice are low responders (LR). The isotype patterns of HR and LR strains differ both quantitatively and qualitatively. In the primary response to doses of 20-100 micrograms DNP-OM, HR strains produce IgM and IgG antibodies, whereas LR strains produce only IgM. Background genes modify the kinetics of the IgGl primary response in HR strains, but no background was found which allowed an IgG response in a LR strain. In secondary responses, priming with 0.2 microgram DNP-OM increases secondary responses in HR strains, and decreases them in LR strains. Control of this response maps to I-A, and is not altered by the bm 12 I-Ab mutation. The LR phenotype is dominant in (HR X LR)F1 mice.

Regulation of experimental autoimmune thyroiditis: influence of non-H-2 genes

Experiments were conducted to investigate the non-H-2 genetic effects on experimental autoimmune thyroiditis (EAT). Strains having C3H or BALB background in general produced higher autoimmune responses to mouse thyroglobulin (MTg) than the B10 or A strains. Comparisons of C3H and B10 congenic strains carrying similar H-2 haplotypes demonstrated that the C3H congenics had significantly higher MTg antibody titres and more severe thyroid damage, even when the strains carry the low responder H-2 haplotypes. These observations show that non-H-2 gene(s) influences EAT, in addition to genes in the MHC.

Antistreptococcal group A antibodies: production after in vitro activation and hybridization of mouse spleen cells

Streptococcal group A polysaccharide-specific antibodies were raised by the method of somatic cell hybridization. Spleen cells of experimentally unprimed BALB/c and C57BL/6 mice were activated in vitro by the streptococcal vaccine and fused with the Sp2/0-Ag14 line at times o, 35, 70, and 105 h thereafter. Hybridomas were obtained at all times independent of the addition of thymocyte-conditioned medium. Occurrence of specific hybridomas for the T cell-dependent A-CHO, however, required activation for greater than 35 h. Low responder C57BL/6 splenocytes fused at considerably higher fusion efficiency to yield specific hybridomas than high responder spleen cells 105 h after activation by antigen. The isotypes of A-CHO-specific antibodies comprised predominantly mu and kappa polypeptides; however, gamma 3, alpha, and gamma polypeptide chains were also identified. All specific antibodies were agglutinating the group A streptococcal cells; this agglutination was fully inhibited by the addition of 1% N-acetyl-D-glucosamine, the immune determinant sugar of the A-CHO. Three hybridomas obtained by fusion of BALB/c splenocytes 105 h after activation were cloned and grown as tumours in the peritoneal cavity of BALB/c mice. The monoclonal antibodies in the ascites did not precipitate the A-CHO but continued to agglutinate group A streptococcal cells in a hapten inhibitable fashion with different specificity profiles. Antibody from clone 21S36.1 was coprecipitable upon addition of A-CHO with a gamma G3 monoclonal hybridoma-derived antibody in a ratio of 1/7 while the other two monoclonal gamma M antibodies and the S117 myeloma protein were not. The result suggests that antibody 21S36.1 recognizes one chain terminal determinant of the A-CHO.

Immune response deficiency of BSVS mice. II. Generalized deficiency to thymus-dependent antigens

BSVS mice gave abnormally low IgG responses to 5 thymus-dependent antigens as well as a weak delayed-type hypersensitivity (DTH) response to sheep red blood cells. In contrast to IgG, the IgM antibody responses of these mice were normal to three T-independent antigens as well as to all five T-dependent antigens. The low immune responsiveness of BSVS mice was also reflected in the low levels of IgG(2)a, IgG(2)b and IgG(3) in their normal serum. The low T-dependent immune responses may result from BSVS mice having been selectively bred for susceptibility to infection with St. Louis encephalitis virus and Salmonella. C57BL/6J mice, which are also highly susceptible to Salmonella, gave low immune responses similar to, but genetically distinct from, those of BSVS mice. The levels of Ig-positive and theta-positive cells were normal in BSVS and C57BL/6J mice.