The oral administration of human thyroglobulin does not affect the incidence of lymphocytic thyroiditis in the biobreeding Worcester rat

Oral tolerization with the appropriate antigen(s) to ameliorate autoimmune diseases in humans and in experimentally induced animal models, including e xperimentally autoimmune thyroiditis in mice, has been reported to be effic acious. Spontaneous and iodine induced (0.05% iodine in the drinking water) lymphocytic thyroiditis (LT) occurs in the diabetes mellitus (DM)-prone Bi oBreeding/Worcester (BB/Wor) rat. The present study was carried out to dete rmine whether the oral administration of human thyroglobulin (hTg) would de crease the incidence of spontaneous and iodine-induced LT in the BB/Wor rat . Low iodine content hTg or bovine serum albumin (BSA) were given orally ev ery 2 days for six doses beginning at age 50 days to BB/W rats, half of who m also received iodine in their drinking water. No effect or orally adminis tered hTg was observed on thyroid weight, the incidence of LT or DM, or on serum thyroglobin antibodies (TgAb), thyrotropin (TSH), thyroxine (T-4), an d triiodothyronine (T-3) concentrations when rats were killed at 100 days o f age. In a second experiment, the oral administration of iodine rich hTg o r BSA every 2 days for six doses beginning at 30 days of age to iodine-trea ted BB/Wor rats again did not affect the high incidence of LT or DM or seru m TgAb, TSH, T-4, and T-3 concentrations. The present study suggests that o ral tolerization with hTg does not affect spontaneous or iodine-induced lym phocytic thyroiditis or serum thyroglobulin antibodies in the BB/Wor rat.