Implantation and early pregnancy: Endometrial Th2 cytokine expression throughout the menstrual cycle and early pregnancy

Embryonic implantation and maintenance of pregnancy is influenced by the maternal immunological response. Type 2 T-helper (Th2) cells secrete interleukins 4, 5, 6 and 10 and are associated with suppression of cell-mediated immunity. Temporal changes in the expression of these cytokines were detectable by immunohistochemistry throughout the menstrual cycle. In pregnancy, 10-fold or greater increases in interleukin 6 and 10 secretion were detectable by enzyme-linked immunoassay compared with the non-pregnant state. The pattern of expression of Th2 cytokines suggests that progesterone may influence endometrial cytokine secretion. During pregnancy, Th2 expression paralleled that of vimentin, a stromal cell marker, suggesting that these cells may be a principal source of Th2 cytokines may be a mechanism of suppressing cell-mediated immunity in the endometrium, which may in turn enhance embryonic implantation and maintenance of pregnancy.