The nature of the autoantibody response to thyroglobulin in murine strains with high or low susceptibility to the experimental induction of autoimmune thyroiditis.

A sensitive three-layer solid phase immunoradiometric assay for estimating thyroglobulin antibodies in different mouse immunoglobulin subclasses was established and applied to study the subclass distribution of these antibodies in strains of mice differing in their susceptibility to the development of experimental autoimmune thyroiditis. Low response could not be ascribed to failure to produce a particular subclass. However, the absolute antibody levels in susceptible strains tended to be much higher, particularly in the IgG1, IgG2a and IgG2b classes 2 weeks after immunization. These differences in IgG1 and IgG2a persisted for a further 5 weeks but were less marked in the other subclasses. It would appear that antibody levels may be important in pathogenesis but since mice with high titres of thyroglobulin antibodies do not invariably develop thyroiditis, it is likely that further factors may be involved.