T‐CELL SENSITIZATION TO AUTOLOGOUS THYROID CELLS AND NORMAL NON‐SPECIFIC SUPPRESSOR T‐CELL FUNCTION IN GRAVES' DISEASE

We have employed a syngeneic system utilizing thyroid cell monolayers initiated following thyroid surgery co‐cultured with autologous T cells to demonstrate T cell autosensitization in patients with GRAVES' disease. Antigen‐induced blasto‐genesis was monitored using 24 h [³H]thymidine uptake. Control experiments with 5 d cultured normal human thyroid cells from tissue around benign adenomata showed no evidence of syngeneic T cell autosensitization. Human thyroid cells alone were unable to incorporate [³H]thymidine in the presence of bTSH. In three of four experiments with GRAVES' thyroid cells there was significant induction of autologous T cell blastogenesis with a mean stimulation index of 220%. In parallel experiments we explored the non‐specific helper and suppressor T cell function of these and similar patients with GRAVES' disease. In normal controls (n= 6) increasing numbers of T cells added to a constant number of B cells (consisting of a T cell depleted peripheral mononuclear cell preparation) showed a marked helper effect measured as increasing IgG secretion. As the ratio of T:B cells increased above 4:1 there was a suppression of IgG secretion. One of two hyperthyroid GRAVES' patients was observed to have deficient T cell function as demonstrated by lack of IgG suppression. The remaining five patients (all but one of whom were euthyroid at the time of testing) had results similar to the controls indicating normal suppressor T cell function in this disease. Such data showed that patients with GRAVES' disease possessed circulating T cells which exhibited autosensitization to syngeneic thyroid cell surface antigens, a phenomenon not demonstrable in control individuals. Furthermore, this specific T cell autosensitization did not interfere with non‐specific T cell function as judged by its influence on IgG secretion.