Functions of Macrophages in Human Decidual Tissue in Early Pregnancy

PROBLEM: Roles of decidual macrophages (DMs) in the maintenance of early pregnancy was determined by comparing three of their functions, antigen presentation, immunoregulation, and lymphokine production, with those of peripheral monocytes (PMos) isolated from the same subjects. METHOD: The antigen‐presenting capacity of DMs was examined by the one‐way mixed lymphocyte reaction (MLR) in which accessory cell‐depleted mononuclear cells isolated from pregnant women were used as responders. The effect of DMs on cellular immunity was investigated by inhibition tests of either one‐way MLR or phytohemagglutinin stimulation. The production of interleukin‐1 (IL‐1) and prostaglandin E 2 (PGE 2 ) by DMs following lipopolysaccharide stimulation was examined. RESULTS: Addition of increasing concentrations of DMs to the culture resulted in a concentration‐dependent proliferative response, as well as with PMos. In both assays, a stronger suppression was observed in the presence of DMs from normal pregnant women compared with PMos from the same subjects. DMs were found to secrete significantly lower levels of IL‐1 α and IL‐1β than PMos. No difference in PGE 2 production was observed between DMs and PMos. CONCLUSIONS: These findings suggest that DMs present in human early decidual tissue have a capacity for allo‐antigen presentation, a higher suppressive activity, and a lower capacity to produce IL‐1 than their peripheral counterparts.