Quantitative comparison between biological and immunological activities of prolactin derived from human fetal and maternal sources.

The biological (BA) and immunological (IA) activities of human PRL have been determined in samples of decidual incubation medium, amniotic fluid, and maternal and fetal cord sera obtained from cesarean sections performed at term. PRL from each of the four compartments was assayed using the Nb2 node rat lymphoma cell line and homologous RIA. BA to IA ratios of PRL, when compared within and between compartments, indicate that the BA of PRL from each compartment is equivalent to that of its IA. Thus, the BA of PRL from decidual incubation medium and amniotic fluid was found not to differ from that of pituitary PRL. These data suggest that PRL produced by decidua and found in amniotic fluid is a biologically active hormone.