Antibodies to dissociated cerebellar cells in New Zealand mice as demonstrated by immunofluorescence

The presence of an antibody in New Zealand Black (NZB) mice to dissociated cerebellar cells from 6-10 day-old BDF₁ mice was detected by indirect immunofluorescence. The sera from NZB mice displayed a significantly higher binding to cerebellar cells by this technique than did the sera from two non-autoimmune strains (BDF₁ and CAF₁). The NZB sera showed a positive correlation between an index of cytotoxicity to cerebellar cells and the percentage of cerebellar cells showing serum immunoglobulin (Ig) binding. The NZB sera also showed a significant positive correlation between IgM binding and cytotoxicity to cerebellar cells. No relationship was seen between IgG₁ and IgG₂ fluorescence and the index of cytotoxicity. In addition, in none of the mice was there a positive correlation between levels of thymocytotoxicity and binding by any of the tested classes of immunoglobulin to dissociated cerebellar cells. Further characterization of the antibody using Sephadex G-200 fractionation of NZB sera showed Ig binding to cerebellar cells for peaks I (void volume) and II of the three major peaks. Pooled normal mouse sera showed elevated Ig fluorescence in only the second peak. In all cases, the heightened fluorescence was determined to be IgM when the appropriate fluoresceinated antisera was used. The data suggest the presence, in some NZB mice, of an IgM antibody reactive with componets of the central nervous system.