Effect of 17 beta-estradiol on immunoglobulin secretion by human tonsillar lymphocytes in vitro

Sex steroid hormones play a role in the complex network of immune responses but the mechanism of their action is still unclear. Effects of a wide range of doses of 17 beta-estradiol (E2: 0.2-100 ng/ml) on human tonsillar lymphocyte cultures were examined. B and T lymphocyte enriched preparations were stimulated with various concentrations of interleukin-2 and the production of immunoglobulin was measured. Addition of E2 increased B cell immunoglobulin production in a T cell dependent way with intact T cells being obligatory. The effects of E2 were also examined on DNA synthesis by tonsillar T cells. E2 alone caused a significant increase in T cell DNA synthesis. With phytohaemagglutinin-stimulated T cell cultures there was a significant increase in DNA synthesis with E2 at pharmacological doses. Different cell surface and activation markers (including CD25, p75, HLA-DR, CD28) on tonsillar lymphocytes were also studied after exposure to E2. The presence of E2 made no significant difference in the expression of the markers either alone or when the activation antigens were induced by other stimuli. We have shown that intact T cells are needed for the action of E2 on tonsillar B lymphocyte differentiation and have excluded several mechanisms of action of E2 since common activation antigens are unaffected.