PROBLEM: Due to the lack of classical HLA antigens on the trophoblast, fetal antigens are possibly presented in a non major histocompatibility complex (MHC) restricted way. Decidual γδ T cells, which significantly increase in number during pregnancy, might play a role in recognition of fetal antigens and also in determining the quality of the response to these antigens. Our study was aimed at investigating the role of this cell population in progesterone-dependent immunomodulation.
METHOD OF STUDY: Peripheral lymphocytes from healthy pregnant women and from habitual aborters were tested by immunocytochemistry for the presence of γ/δ T cell receptor (TCR) and progesterone receptor. To investigate the effect of treatment with a pan anti γ/δ antibody, lymphocytes were incubated for 3 hr with the antibody, and then interleukin (IL)-10, IL-12 and progesterone-induced blocking factor (PIBF) expression (by immuno-cytochemistry) as well as natural killer (NK) cell activity were determined.
RESULTS: In peripheral blood of healthy pregnant women the percentage of γ/δ TCR + cells was significantly higher (P < 0.001) than in that of recurrent aborters or of non-pregnant individuals. Ninety-seven percent of γ/δ TCR + pregnancy lymphocytes expressed progesterone receptor. Binding of a specific antibody to the γ/δ TCR inhibited PIBF- as well as IL-10 production, whereas it increased NK activity and IL-12 expression.
CONCLUSIONS: These data suggest the role of γ/δ TCR-bearing lymphocytes in progesterone-dependent immunomodulation.