Different responses of lymphocyte to human placenta conditioned medium in vitro

Several cytokines appear to be implicated in peri-implantation events and in maternal-fetal interaction. The majority of these molecules appear in supernatants or in extracts of placental origin. The purpose of this study was to investigate the action of human placenta conditioned medium (HPCM) on peripheral lymphocytes in vitro. Peripheral lymphocytes of women with different numbers of deliveries, of nulliparous and pregnant women, as well as of men, were cultivated in their own plasma with and without HPCM at 5%, 10% and 20%. The index of lymphocyte blast transformation (ILBT) was determined (values of > or = 0.5 indicated stimulation). In women who had had children, the highest lymphocyte blastogenesis was observed with HPCM at 10%, this finding being correlated to the numbers of deliveries (r = 0.828). In pregnant women, even though the highest answer was also obtained with HPCM at 10%, the addition of suboptimal concentration of HPCM (5%) produced blastic transformation (IBLT: x = 0.54 +/- 0.05), which was not observed in women who had had children. Lymphocytes of men and nulliparous women did not respond to any of the HPCM concentrations tested. In conclusion, HPCM at 10% was still the best concentration to produce lymphocyte blastogenesis. In addition, in the plasma of pregnant women, there may be some substance that enhanced the action in vitro of the extract, thus permitting threshold reduction necessary for lymphocyte stimulation.