Immunodepression in thyroid-deprived animals

Abstract

The removal of the thyroid gland in newborn or in young adult rats causes reduction in the number of peripheral blood lymphocytes and depression of either the humoral immune reactions against sheep and chicken red blood cells or the response of spleen cells to phytohaemagglutinin. These immunological defects are fully established in perinatally thyroidectomized rats after weaning, while in animals thyroidectomized in young-adult age they are observable 45–60 days after the operation. In both cases daily injections with thyroxine can completely restore the lymphoid system of thyroid-deprived animals. These results stress the importance of thyroid hormones for lymphocyte proliferation either during the period of ontogenetic development or in adult life.