[A study on immunological significance of prostaglandins -immunological significance of prostaglandin E in the endometrium around the implantation (author's transl)].

A number of studies have been reported providing indirect evidence of maternal immune response to fetus based on the data from peripheral blood of pregnant women, but little information is available on maternal local immune response at the endometrium involved in control of fetus rejection occurring around the time of implantation. Proliferative response of lymphocytes was measured in phytohemagglutinin (PHA)-stimulated cultures in the presence of prostaglandins of the E series (PGE). When present in the culture at concentration of 10(2) ng/ml, physiological level in the secretory endometrium, PGE inhibited H3-thymidine (H3-TdR) incorporation by 50% of the control. The inhibitory effect was found not to be antagonized by polyphloretin phosphate or di-4-phloretin phosphate. Thus, effects of PGE in the endometrium on lymphocytes and uterine smooth muscle appear to be independent processes. When PGE was added at the beginning of culture, H3-TdR incorporation was suppressed most markedly. However, when added late during the activation process, the suppression was reduced. When PGE was in culture for 12 h and was removed by washing the cells before the addition of PHA, the effect of PGE was negated. These data indicate that effect of PGE affect the early period of the inductive phase of the immune response and is reversible. The significance of such a effect of PGE is discussed in connection with the nonspecific immunosuppression in the secretory endometrium preceding nidation.