Effect of growth hormone administration on thymus size, peripheral T lymphocyte and T lymphocyte subsets in growth hormone deficiency

Experimental evidence suggests that growth hormone (GH) has an important role in the development of T lymphocytes within the thymus. In this study, we investigated the effect of 3-month therapy with GH on the peripheral T lymphocytes, T lymphocyte subsets and thymus size with magnetic resonance imaging measurement of GH-deficient children. We found that GH-deficient chlidren had smaller thymi when compared with healthy age-matched children, but their peripheral T lymphocytes and T lymphocte subsets were within normal range. There were no changes in the total peripheral T lymphocytes and T lymphocte subsets, but thymus size significantly increased wtih GH administration. These findings suggest that GH acts as a thymopoietic agent without any effect on the number of peripheral T lymhocytes.