Recently we reported on a novel H2E transgenic, IA-negative model of experimental autoimmune thyroiditis (EAT) that excludes reactivity to self in its susceptibility pattern to heterologous thyroglobulin (Tg). In conventional, susceptible mouse strains, EAT is inducible with both homologous and heterologous Tg; e.g., human (h)Tg shares conserved thyroiditogenic epitopes with mouse (m)Tg. However, when an H2Ea(k) transgene is introduced into class II-negative B10.Ab(0) mice, which express neither surface IA (mutant Abeta-chain) nor surface IE (nonfunctional Ea gene), the resultant H2E(b) molecules are permissive for EAT induction by hTg, but not self mTg. Also, the hTg-primed cells do not cross-react with mTg. To explore this unique capacity of E+B10.Ab(0) mice to distinguish self from nonself Tg, we have developed T cell lines to examine the T cell receptor repertoire and observed a consistent Vbeta8+ component after repeated hTg stimulation. Enrichment and activation of Vbeta8+ T cells by either superantigen staphylococcal entertoxin B or anti-Vbeta8 in vitro enabled thyroiditis transfer to untreated A-E+ recipients, similar to hTg activation. Vbeta8+ T cells isolated by FACS from hTg-immunized mice also proliferated to hTg in vitro. These studies support the contribution of Vbeta8 genes to the pathogenicity of hTg in this H2A-E+ transgenic model.