GENDER DIFFERENCES IN IL-1-ALPHA, IL-1-BETA, AND IL-1 RECEPTOR ANTAGONIST SECRETION FROM MONONUCLEAR-CELLS AND URINARY-EXCRETION

Previous studies have reported increased secretion of IL-1-like activi ty from mononuclear cells and increased circulating levels during the luteal phase of the menstrual cycle. In this investigation, specific R IAs for the agonists IL-1 alpha and IL-beta as well as IL-1 receptor a ntagonist (IL-1Ra) were used to determine whether differential IL-1 se cretory patterns exist between men and women or between phases of the menstrual cycle. Mononuclear cells were isolated from six men and five women at 4-h intervals from 8 am to 8 pm, with the women studied once in midfollicular phase and once in midluteal phase. In the absence of any intentional stimulation, significant differences in secretion wer e observed between groups (p < 0.03) for all three species of IL-1: wo men's cells isolated during the luteal phase secreted 5- to 10-fold mo re than cells from men, and women's cells isolated during the follicul ar phase secreted 13- to 28-fold more than cells from men. In addition , total 24-h urine samples were collected in intervals with end points coinciding with the blood samples. Urinary excretion correlated with cellular secretion for IL-beta and IL-1Ra (p = 0.024 and 0.028, respec tively), indicating that the in vitro results may correspond to differ ential processes occurring in vivo. Although greater absolute amounts of each species of IL-1 were secreted during the follicular phase, the ratio of agonist to antagonist secreted was greater in the luteal pha se (p < 0.05), in agreement with previous studies of bioactivity. Thes e results indicate that the regulation of IL-1 secretion is fundamenta lly different in women compared with men and alludes to the possibilit y that IL-1 may serve different biologic functions in women than men.