Sex hormone levels correlate with the activity of cytokine-secreting cellsin vivo

This work examines the correlation between serum levels of oestrogen, proge sterone and dehydroepiandrosterone sulphate (DHEA-S) and the number of huma n peripheral blood cells actively secreting interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-g amma) in vivo. Simultaneous assessment of serum hormone levels and cytokine -secreting cell activity throughout the menstrual cycle showed that the num ber of peripheral blood mononuclear cells (PBMC) able to secrete IL-4 in re sponse to stimulation correlated significantly (P < 0.0001) with oestrogen levels and fluctuated with the menstrual cycle in pre-menopausal women. The activity of IFN-gamma-secreting cells, on the other hand, varied as a func tion of serum DHEA-S levels in pre-menopausal women (P < 0.0001). Similarly , the number of cells secreting IFN-gamma in men correlated with serum DHEA -S levels (P < 0.001). In contrast, post-menopausal women had fewer cells a ctively secreting cytokines and the activity of these cells did not correla te with sex hormone levels. These results suggest that sex hormones may mod ulate cytokine production in vivo and contribute to gender-related differen ces in normal and pathological immune responses.