The effect of T cell subset depletion on autoimmune thyroiditis in the Buffalo strain rat.

The aim of these experiments was to analyse the functional roles of phenotypically defined T cells from Buffalo strain rats with immunisation or neonatal thymectomy-induced autoimmune thyroiditis. Rats were depleted either of CD8-positive T cells by administration of the Ox8 monoclonal antibody or of activated T cells by administration of low-dose cyclosporin A (Cs A) with an anti-IL-2 receptor monoclonal antibody (ART-18), and the effects on subsequent disease assessed. Even though animals were not completely depleted of Ox8 cells, immunisation-induced thyroiditis was enhanced by Ox8 treatment, whereas thyroglobulin antibodies were reduced compared with controls. Subtherapeutic doses of either Cs A or ART-18 alone had little effect on thymectomy-induced thyroiditis, in contrast to Cs A and ART-18 in conjunction, which prevented disease developing. These results suggest important roles for CD8-positive and IL-2 receptor-bearing T cells in experimental autoimmune thyroiditis.