[Immunosuppressive effect of culture supernatant derived from decidual cell rich fraction]

The immunosuppressive function of culture supernatant of decidual cell rich fraction (Dec. supp.) was studied with the aim of clarifying the role played by decidual tissue in maintaining pregnancy. To obtain decidual cells, decidual tissue from miscarriages was enzyme-treated and submitted to Percoll discontinuous specific gravity centrifugation in specific gravity fractions from 1,025 to 1,065 in steps of 0.01. Decidual cell rich fraction was obtained in specific gravity fractions at 1,035 and 1,045. The Dec. supp. was obtained by incubating the decidual cell rich fraction for 24 hours. The effects on cell-mediated immunity were studied with the PHA reaction of mononuclear cells (MNC) and the one-way mixed lymphocyte reaction (MLR) among normal subjects. For the PHA reaction, suppression was 19.5 +/- 7.8% and 38.2 +/- 8.9% after the administration of Dec. supp. at 20% and 50% respectively. For the MLR, conspicuous suppression of 48.0 +/- 19.1% and 61.0 +/- 31.2% was seen after administration at 20% and 50% respectively. Next, indomethacin (ind.), a synthetic suppressor of prostaglandin (PG), was added in order to determine what part PG in the culture supernatant plays as one of the immunosuppressive factors in Dec. supp. Suppression was notably weaker. The PGE density in Dec. supp. was measured and found to be as high as 840 +/- 350 pg/ml, which suggests the possible intervention of PG as one of the suppressing factors.