Strong suppression by mononuclear leukocytes from human newborns on maternal leukocytes: Mediation by prostaglandins

Abstract Two prostaglandin synthetase inhibitors, indomethacin and 5,8,11,14-eicosatetraynoic acid (ETYA), were evaluated in vitro for their effect on the interaction between phytohemagglutinin (PHA)-stimulated leukocytes from human newborns and their mothers. The reaction was studied in a double chamber unit partitioned by a semipermeable membrane and in cocultures assayed by a fluorescent chromosome technique with the Y-chromosome used as a marker to distinguish dividing male cells from maternal cells. A dialyzable factor(s) produced by newborns' leukocytes suppressed mitoses of maternal leukocytes. ETYA abrogated this suppression and indomethacin in addition also reversed the response by stimulating mitoses. In cocultures indomethacin diminished or abrogated the strong suppressive effect of newborns' leukocytes on maternal leukocytes. Leukocytes from newborns had a mutual enhancing effect on each other in the double chamber assay. Indomethacin increased this enhancing effect. Our findings thus indicate that newborns' mononuclear leukocytes suppress their mothers' mononuclear leukocytes by a prostaglandin-mediated mechanism and that both stimulatory and inhibitory products of arachidonic acid metabolism may be involved.