Differences in binding sites for prostaglandin E2 on mononuclear leucocytes from human newborns and from their...

Binding of [3H]prostaglandin E2 (PGE2) to peripheral mononuclear leucocytes (PML) from newborns and their mothers was studied. Specific binding of PGE2 to both maternal and neonatal PML was found. The binding was maximal after 15 min of incubation at 37 degrees C and specific for PGE1 and PGE2 versus PGA1, PGF1 alpha, and PGF2 alpha. The amount of PGE2 specifically bound to neonatal PML was about 30% of the amount bound to maternal PML. The average number of binding sites for PGE2 on maternal PML was calculated to 1800 per cell, and the dissociation constant (KD) was 6.5 X 10(-9)M. The corresponding figures for neonatal PML could not be calculated owing to the low number of binding sites on those cells. After preincubation for 18 h the binding of PGE2 to maternal PML was decreased and equalled that of PGE2 to neonatal PML, whereas neonatal PML were unaffected by preincubation. These results indicate that differences in sensitivity to suppression by PGE and the effect of preincubation may be linked to differences in binding of PGE.