Decidual-trophoblast interactions: decidual lymphoid cell function in normal, anembryonic, missed abortion and ectopic human pregnancy.

This study was designed to investigate the consequences of decidua-trophoblast interactions on the phenotype, spontaneous and induced proliferation and immunoregulatory potential of decidual leukocytes in normal pregnancies (NP), anembryonic pregnancies (AP), missed abortions (MA) and ectopic pregnancies (EP). Spontaneous proliferation of decidual non-adherent cells (NAD) from pregnancies with viable trophoblast inside the uterus is significantly higher than proliferation of peripheral blood lymphocytes (PBL) from the same groups (P < 0.001 for NP; P < 0.05 for AP). Spontaneous proliferation of decidual NAD cells from NP was higher (P < 0.001) when compared with AP and EP. The induced (PHA and Con A) responses of PBL from women with normal and pathological pregnancies were significantly higher than that of decidual NAD cells (P < 0.001). Higher proliferation of NAD decidual cells was obtained when Con A-stimulated NP were compared with MA and EP (P < 0.01). The interaction of viable trophoblast with intrauterine decidua appears to be a prerequisite for the activation of NAD suppressor cells, since NAD cells from MA produced stimulation instead of suppression, and NAD cells from EP had no suppressive effect. On the contrary, both NAD and adherent (AD) decidual leukocytes from NP and AP produced very strong suppression of PHA or alloantigen-induced PBL proliferation. The contact between trophoblast and AD decidual leukocytes is not necessary for their suppressive function, since even higher suppression is obtained with the cells from ectopic pregnancies.