Immunomodulatory role of thyroid hormones: in vivo effect of thyroid hormones on the blastogenic response of lymphoid tissues

Abstract

To find out the mechanism of immunomodulation by thyroid hormones (T3 and T4 [thyroxine and triiodothyronine]), their in vivo effect on the blastogenic response of lymphocytes from various lymphoid tissues of hormone-treated and thyroidectomized rats were studied. The blastogenic response of lymphocytes from thymus, peripheral blood and meseneteric lymph nodes to pokeweed mitogen (PWM) was increased significantly following T3 or T4 administration for 15 days or 30 days. The response to phytohemagglutinin (PHA) increased only after 1 mo. of T3 or T4 administration. The blastogenic response of spleen cells to PHA and PWM was depressed following 15 days of hormone administration. Thyroidectomy invariably induced significant depression in the blastogenic response to PHA and PWM in lymphocytes of all the lymphoid tissues. Thyroid hormone (T3) administration restored the blastogenic response of the blastogenic response of the lymphocytes of thyroidectomized animals.