The immune response during the luteal phase of the ovarian cycle: a Th2-type response?

OBJECTIVE To test the hypothesis that during the luteal phase of the ovarian cycle, as compared with the follicular phase, the peripheral immune response is shifted toward a type-2 response. DESIGN Prospective study. SETTING Academic research setting. PATIENT(S) Women with regular menstrual cycles. INTERVENTION(S) Blood samples were collected between days 6 and 9 of the menstrual cycle and 6-9 days after the LH surge. MAIN OUTCOME MEASURE(S) Intracellular cytokine production of interferon (IFN)-gamma, interleukin (IL)-2, IL-4, and IL-10 after in vitro stimulation of lymphocytes as well as total white blood cell (WBC) count, differential WBC count, and plasma 17 beta-E(2) and P concentrations. RESULT(S) Mean plasma 17 beta-E(2) and P concentrations, WBC count, and mean granulocyte, monocyte, and lymphocyte counts were significantly increased in the luteal phase as compared with the follicular phase of the ovarian cycle. Production of type-1 cytokines (IFN-gamma and IL-2) and production of the type-2 cytokine IL-10 did not vary between the phases of the ovarian cycle. Production of the type-2 cytokine IL-4, however, was significantly increased in the luteal phase as compared with the follicular phase of the ovarian cycle. CONCLUSION(S) During the luteal phase of the ovarian cycle, the immune response is shifted toward a Th2-type response, as reflected by increased IL-4 production in this phase of the cycle. These results may suggest that increased levels of P and 17 beta-E(2) in the luteal phase of the ovarian cycle play a role in the deviation of the immune response toward a type-2 response.