Interferon-related and other immune genes are downregulated in peripheral blood leukocytes in the luteal phase of the menstrual cycle.

Interaction between the endocrine and the immune systems has been suggested by observations of sexual dimorphism of the immune response, differential susceptibility to autoimmunity between the sexes, changes in autoimmune disease activity during the menstrual cycle and in pregnancy and in vitro studies of hormonal influence on cytokine production.We hypothesized that if there is hormonal regulation of the immune response, this would be manifest in peripheral blood leukocytes (PBLs) at different phases of the menstrual cycle. In this study, we describe gene profiling of PBLs from the follicular and luteal phases of the menstrual cycle. We observe important differences in immune gene expression, with significant down-regulation of the Th1 immune response in the luteal phase. A significant number of interferon (IFN)-related genes are amongst the downregulated genes. These results support significant hormonal regulation of the immune system and may have therapeutic implications in diseases of autoimmunity in women.