INTERLEUKIN-1 SYSTEM IN THE MATERNO-TROPHOBLAST UNIT IN HUMAN IMPLANTATION - IMMUNOHISTOCHEMICAL EVIDENCE FOR AUTOCRINE PARACRINE FUNCTION/

Interleukin-1 receptor type I, IL-1 beta, IL-1 receptor antagonist, an d human macrophages were immunohistochemically localized in the villou s trophoblast, maternal-trophoblast interphase, and maternal decidua d uring early human implantation. Immunostaining for IL-1 receptor type I was present in the syncytiotrophoblast and hyperplastic endometrial glands in the maternal decidua. Immunoreactive IL-1 beta was present i n the villous cytotrophoblast, syncytiotrophoblast, intermediate troph oblast, and maternal stromal decidual cells. IL-1 receptor antagonist staining was observed in the glandular endometrium of the maternal dec idua and in isolated cells located inside the chorionic villi, intervi llous space, and maternal decidua. Mature human macrophages, as define d by both CD/68(+) and HAM56(+), were present in the chorionic villi, maternal blood of intervillous space, and maternal decidua. Colocaliza tion studies demonstrated that macrophages in all of the reported loca tions also stained for immunoreactive IL-1 beta. Our results show the shared presence in maternal and embryonic tissues of this receptor-ago nist-antagonist system during early human implantation. This finding s upports an autocrine/paracrine role for the IL-1 system in human impla ntation.