Immunoregulatory activity of decidua in spontaneous early pregnancy loss

The present study aimed to address whether the immunoregulatory properties of the molecules secreted within decidua were altered in women suffering sp ontaneous miscarriage, compared with apparently normal fertile women. Unfra ctionated decidual cells from 22 women undergoing therapeutic pregnancy ter minations and 25 women experiencing a sporadic spontaneous early pregnancy loss were isolated, cultured for 24 h and 72 h, and supernatants were colle cted. The effect of decidual supernatants on phytohaemagglutinin (PHA)-indu ced peripheral blood lymphocyte proliferation was investigated. Immunosuppr essive activity was detected in 24 h cell culture supernatants from 91% of therapeutic abortion cases compared with only 64% of spontaneous abortion s amples; 72 h supernatants from all of therapeutic abortion samples and 90% of spontaneous abortion cases suppressed lymphoproliferation. The remaining spontaneous abortion samples (36% of 24 h supernatants; 10% of 72 h supern atants) enhanced or had no effect on lymphocyte proliferation. Enhancement of lymphocyte proliferation was not observed in therapeutic abortion sample s, and the association between stimulation of cell proliferation and sponta neous abortion was significant for 24 h decidual cell supernatants at 50% c oncentration (P = 0.02). These findings suggest that in a subgroup of women experiencing spontaneous early pregnancy loss, soluble factors within deci dua display altered immune responses that may be implicated in the complex process of fetal rejection.