STABILITY OF SERUM INTERLEUKIN-10 LEVELS DURING THE MENSTRUAL-CYCLE

PROBLEM: Menstrual cycle-associated variability in the circulating lev els of several cytokines can be a confounding factor in measurements o f in vivo cytokine levels in clinical studies. Since pregnancy-associa ted increases in interleukin-10 (IL-10) levels are well documented, we have investigated the variability in serum levels of IL-10 in healthy women at different stages of the menstrual cycle to ascertain whether this is a problem in comparative studies of circulating IL-10 levels. METHOD OF STUDY: We obtained fifty-four successive serum samples at p oints in the menstrual cycles of 12 healthy fertile women, precisely t imed by measurement of the luteinizing hormone surge, and measured the interleukin-10 levels. RESULTS: Levels of IL-10 in successive serum s amples from each woman taken on days LH-7 (that is seven days prior to LH surge), LH-4, LH+1, LH+7, and LH+10 showed that IL-10 does not var y in a systematic way during the menstrual cycle. CONCLUSION: These re sults validate the sampling of women in studies of IL-10 levels in var ious clinical situations and establish that these levels are not depen dent on menstrual cycle dates. They also suggest that menstrual cycle- related changes in IL-1 are not mediated by IL-10. The rise in progest erone in the luteal phase of the menstrual cycle is not mirrored by a rise in the circulating IL-10 level, which implies either that the pre gnancy-associated rise is not related to progesterone or that it is on ly observed at the higher progesterone levels in pregnancy.