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

Objective: To distinguish endocrine and paracrine influences on leukocyte subpopulations at uterine and tubal implantation sites. Design: Retrospective immunohistochemical study. Setting: Departments of Anatomy, and Obstetrics and Gynecology, School of Medicine, RWTH University of Aachen, Aachen, Germany. Patient(s): Ten women with a viable ectopic pregnancy (EP), 25 women who had 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 leukocyte subpopulations at the implantation sites and their corresponding noninvaded tissues, decidual tissue from patients with EP, and tubal mucosa from normal menstrual cycle. Result(s): Similar numbers and characteristic distribution patterns of macrophages, T cells, and B cells were found at both normal intrauterine and tubal implantation sites. Natural killer (NK) cells were always absent from tubal mucosa. The number and distribution of leukocytes within decidual tissue from women with EP corresponded to those in the noninvaded decidual compartment in intrauterine pregnancy (IUP). Conclusion(s): Leukocyte populations present in the tubal and uterine mucosa are an intrinsic characteristic of these tissues. The distinct leukocyte distribution pattern at the implantation sites suggests that the invading trophoblast exerts a paracrine influence on endometrial and endosalpingeal leukocytes. 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.