Decidual leucocyte populations in women with pre-eclampsia

Abstract

Successful pregnancy is a carefully regulated balance of stimulatory and inhibitory immune mechanisms, dysregulation of which may generate harmful immune responses leading to pregnancy disorders. Evidence in the mouse suggests that the uterine vascular changes and altered trophoblast invasion in women with pre-eclampsia (PE) may be caused by altered maternal immune responses within the decidua. We tested the hypothesis that cytotoxic decidual leucocyte populations (CD3⁺, CD8⁺ and CD56⁺) are altered in women with PE. Placental bed biopsies from 12 women with PE [mean (SD) gestation 34.3 (4.5) weeks] and 12 women with normal pregnancies [36.8 (3.6) weeks] were studied using single immunohistochemical labelling (avidin–biotin complex method) and, where appropriate, double labelling (APAAP method) to detect CD3⁺, CD8⁺ and CD56⁺ leucocyte populations. Positively labelled decidual leucocytes were counted in five randomly selected fields. Compared with decidua from normal pregnancies, PE decidua contained fewer CD3⁺ cells [mean (SD) 40.3 (6.8) vs. 20.4 (1.9) cells per ×250 field, P < 0.01], CD8⁺ cells [34.8 (5.5) vs. 19.4 (2.6), P < 0.05] and CD56⁺ cells [29.0 (3.3) vs. 18.3 (1.9) cells per ×250 field, P < 0.01]. The reduction in each population of cytotoxic leucocytes was confirmed by double labelling.