The release of thyroglobulin from the thyroid gland into thyroid lymphatics; the identification of thyroglobulin in the thyroid lymph and in the blood of monkeys by physical and immunological methods and its estimation by radioimmunoassay.

The iodoprotein which was found in the lymph draining from the thyroid gland of monkeys has been identified as thyroglobulin, both by physical and by immunological techniques. A sensitive and highly specific radioimmunoassay was developed by which thyroglobulin has been estimated in the thyroid lymph and in the blood of these animals. Small but appreciable concentrations of thyroglobulin were found in thyroid venous and in peripheral blood. Non-thyroid lymph did not usually contain detectable concentrations of thyroglobulin but thyroglobulin was regularly found in thyroid lymph, sometimes in high concentrations. Thyroid stimulating hormone raised the concentration of thyroglobulin in the thyroid lymph still higher as did gentle massage of the tissues overlying the gland. It was shown that the release of thyroglobulin into the thyroid lymph was a normal physiological process, for the possibility that it might have been released as a result of radiation or operative damage to the thyroid gland was excluded by experiments in which the need for administration of radioisotope to the animals was avoided and in which samples of lymph were obtained by cannulation of a cervical lymphatic trunk at some distance from the thyroid gland itself. The implications of these findings are discussed in relation to the autoimmune phenomena seen in human thyroid disease.