Effects of stage of the estrous cycle and steroid treatment on uterine immunoglobulin content and polymorphonuclear leukocytes in cattle

Abstract

Studies were performed to determine 1) cyclic changes in uterine immune function that could be responsible for the increased susceptibility of the diestrous uterus to infection and 2) whether these changes are mediated by progesterone or estradiol-17 β. The number and functional activity (cytochrome creduction) of polymorphonuclear leukocytes (PMNL) collected from the uterus after oyster glycogen infusion was not statistically affected by stage of the cycle or steroid treatment. While not significant, the number of PMNL tended to be higher at diestrus than at estrus. The number of PMNL also tended to be higher for ovariectomized cows treated with progesterone than with estradiol-17 β or vehicle. For cows given oyster glycogen, uterine IgG was not significantly affected by treatment and uterine IgA was undetectable. For ovariectomized cows not given oyster glycogen, IgA was detectable in uterine flushings and was higher after 30 d of progesterone treatment than after 12 d of progesterone or vehicle. Additionally, the ability of uterine fluid from ovariectomized cows to inhibit mitogen-induced lymphocyte proliferation was greater (P<0.01) for uterine fluid collected from cows treated with progesterone for 12 and 30 d than for cows treated with vehicle. It is concluded that alterations in migration of PMNL are unlikely to be the cause of decreased resistance of the uterus to infection during diestrus. Lowered resistance might, in part, be due to the secretion of uterine factors that inhibit lymphocyte function.