Decrease of T-helper 2 and T-cytotoxic 2 cells at implantation sites occurs in unexplained recurrent spontaneous abortion with normal chromosomal content.

Abstract

In normal pregnancy, predominant type 2 cytokines help maintain pregnancy, and a T-helper (Th)1 type response is associated with unexplained recurrent spontaneous abortion (RSA). However, Th2 and T-cytotoxic (Tc)2 cells have not been localized at the implantation site in RSA. Twenty-one cases with RSA were classified into RSA with normal chromosomal content (RSA-N, n = 10) and RSA with abnormal chromosomal content (RSA-A, n = 11). As a control, we selected 15 gestational age-matched cases of induced abortion with no history of spontaneous abortion. We immunostained paraffin-embedded decidual sections for a specific Th2 and Tc2 cell marker termed 'chemo-attractant receptor-homologous molecule expressed on Th2 cells (CRTH2)' and T-cell markers CD3 and CD8. The numbers and percentages of Th2 (CRTH2(+)CD8(-)CD3(+)) and Tc2 (CRTH2(+)CD8(+)) cells were compared between the decidua basalis and decidua parietalis. Th2 and Tc2 cells accumulated in the decidua basalis in normal pregnancy. Accumulation of Tc2 cells and both Th2 and Tc2 cells decreased in the decidua basalis in RSA-A and RSA-N respectively. The number and percentage of Th2, and Tc2 cells in the decidua parietalis were similar in normal pregnancy, RSA-A and RSA-N. Decreased Th2 and Tc2 cells at the implantation site may contribute to RSA-N.