Leukocyte subpopulations in the human uterine cervical stroma at early and term pregnancy

Leukocyte subsets were detected by immunohistochemical methods in cervicaltissue in either the first trimester or at term pregnancy. In tissueobtained during first trimester lower total numbers of leukocytes wereobserved in comparison with late pregnancy (2.7 cells/0.04 mm2 versus 5.5cells/0.04 mm2). The major subgroup of leukocytes present in earlypregnancy was T-lymphocytes. The majority of these cells were of thesuppressor/cytotoxic subtype. Neutrophils were present at about 1/5th ofthe density of T-lymphocytes. Very few macrophages were observed at thisstage. At term pregnancy, neutrophils were present in significantly highernumbers than during first trimester with no difference between tissueobtained before or during active labour. Macrophages were present at about10-fold higher density than during early pregnancy. In conclusion,tissue-bound leukocytes are present in the human cervix at a higher densityin late pregnancy compared to first trimester. The increased densities ofneutrophils and macrophages at this stage indicate a role for these cellsduring cervical ripening.