Effects of trophoblast invasion on the distribution of leukocytes in uterine and tubal implantation sites

Objective: To distinguish endocrine and paracrine influences on leukocyte s ubpopulations at uterine and tubal implantation sites. Design: Retrospective immunohistochemical study. Setting: Departments of Anatomy, and Obstetrics and Gynecology, School of M edicine, RWTH University of Aachen, Aachen, Germany, Patient(s): Ten women with a viable ectopic pregnancy (EP), 25 women who ha d undergone elective first-trimester termination of pregnancy, and 4 women who had undergone hysterectomy with adnexectomy. Intervention(s): None. Main Outcome Measure(s): Quantitative analysis of le ukocyte subpopulations at the implantation sites and their corresponding no ninvaded tissues, decidual tissue from patients with EP, and tubal mucosa f rom normal menstrual cycle. Result(s): Similar numbers and characteristic distribution patterns of macr ophages, T cells, and B cells were found at both normal intrauterine and tu bal implantation sites. Natural killer (NK) cells were always absent from t ubal mucosa. The number and distribution of leukocytes within decidual tiss ue from women with EP corresponded to those in the noninvaded decidual comp artment in intrauterine pregnancy (IUP). Conclusion(s): Leukocyte populations present in the tubal and uterine mucos a are an intrinsic characteristic of these tissues. The distinct leukocyte distribution pattern at the implantation sites suggests that the invading t rophoblast exerts a paracrine influence on endometrial and endosalpingeal l eukocytes. The absence of natural killer cells from the tubal. wall may be one reason for the higher degree of invasiveness of the trophoblast at the tubal implantation site. (C) 2001 by American Society for Reproductive Medi cine.).