title: Serum IgM/A, IgA and functionally distinct IgM anti-type III pneumococcal polysaccharide (SIII) antibodies in BALB/c and athymic (nude) mice.
abstract: The influence of hereditary absence of thymus upon the synthesis of IgA, complement-fixing (CF) hybrid IgM/A, CF-IgM and non-CF-IgM antibodies to pneumococcal type III polysaccharide (SIII) injected into BALB/c and athymic nude mice was studied. Techniques involved the differential absorption of the serum antibodies by protein-A of Staphylococcus aureus (Sa), coprecipitation in gels with 125I-SIII and autoradiography. IgM/A anti-SIII activity was not demonstrable in nude mice but was produced in significant amounts, by day 5, in BALB/c mice injected with SIII. By day 8, nude mice produced more IgA anti-SIII antibodies than BALB/c mice injected with the same antigen. IgA anti-SIII antibodies were not detected in either strain 5 days after SIII administration. The absence of hybrid IgM/A anti-SIII antibodies in athymic mice, prior to the appearance of monotypic IgA anti-SIII antibodies at day 8, suggests that IgM/A and not IgA synthesis is largely T cell-dependent. The evidence also implies that hybrid IgM/A antibody production, maximal on day 5 in BALB/c mice, and absent from nude mice, is not an essential product in the switching from IgM to IgA synthesis. Both strains of mice produced comparable amounts of complement-fixing (CF)-IgM and NCF-IgM anti-SIII antibodies, with the production of non-complement-fixing (NCF)-IgM anti-SIII in athymic mice being delayed. Results indicate that attempts to quantitate the levels of IgA by assays incorporating anti-IgA anti-sera may be complicated by the presence of IgM/A hybrid antibody.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D003168:Complement Fixation Tests; D005260:Female; D007108:Immune Tolerance; D007070:Immunoglobulin A / Q000096:biosynthesis; D007075:Immunoglobulin M / Q000096:biosynthesis; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D007070:Immunoglobulin A; D007075:Immunoglobulin M; D011135:Polysaccharides, Bacterial; C026604:pneumococcal polysaccharide, type III