Deficient activity of prostacyclin stimulating plasma factor (PSPF) in newborns

The activity of PSPF was studied in 38 normal newborns. The production of 6-keto-PGF1 (PGI2 stable metabolite) after stimulation with cord blood plasma, 0.72 +/- 0.50 pmol/10(5) cells, was lesser than after stimulation with plasma from 2-3 years old children, 3.00 +/- 0.89 pmol/10(5) cells (p less than 0.01), or from adults, 7.74 +/- 5.00 pmol/10(5) cells (p less than 0.001). No differences were shown during neonatal period. The presence of a circulating inhibitor factor in newborns was dismissed by mixed cultures. The behaviour of neonatal plasma after consecutive stimulations with AA was similar to adult plasma response. We proved that newborns show a deficient capacity to stimulate PGI2, which is not due to circulating inhibitor factor, and we think that this deficiency is due to a weaker action of stimuli, rather than to an immaturity.