Spontaneous suppressor cells for mitogen responsiveness of cord blood lymphocytes

Analysis of proliferating lymphocyte subpopulations in newborns and adults

Surface markers of peripheral lymphocyte subpopulations were determined before and after in vitro stimulation of neonatal and adult mononuclear cells with phytohaemagglutinin (PHA) and pokeweed mitogen (PWM). The type of cell responding to each mitogen was identified by a method combining autoradiography and the peroxidase-antiperoxidase (PAP) staining method. In comparison with adults, there is a lower proportion of OKT3-positive lymphocytes in neonates (43% vs. 72%). Analysis of lymphocyte subpopulations after stimulating mononuclear cells with PHA and PWM showed that in neonates nearly the same percentages of OKT4-and OKT8-positive proliferating cells (43% and 40%, respectively) could be observed, whereas in the proliferating cells from the adults, the OKT8 surface marker predominated (41% vs. 18%).

Strong suppression by mononuclear leukocytes from cord blood of human newborns on maternal leukocytes associated with differences in sensitivity to prostaglandin E2

We have tested peripheral mononuclear leukocytes (PML) from the cord blood of newborns, from sera of their mothers, and from sera of nonrelated nonpregnant adult women for sensitivity to suppressive exogenous prostaglandin E2 (PGE2). Endogenous PG production was simultaneously inhibited by indomethacin 2.8 microM. The phytohemagglutinin-stimulated (PHA-simulated) uptake of tritiated thymidine (3H-TdR) by PML from the mothers and the nonpregnant women was suppressed by the exogenous PGE2 at a concentration of 1.4 x 10(-8) M, 100 times less than the one required to suppress the PML from newborns (1.4 x 10(-6) M). In addition, 1.4 x 10(-7) M or less of PGE2 reversed the suppression of neonatal PML to stimulation. The maternal PML were reversed into stimulation at 1.4 x 10(-9) of exogenous PGE2. The amount of endogenous PGE2 synthesized by 1 x 10(6) fresh, nonstimulated neonatal PML according to gas chromatography-mass spectrometry assay was 5 ng (1.4 x 10(-8) M). The synthesis increased to 27 ng/10(6) cells after 18 hours' incubation. These concentrations are similar to the ones of exogenous PGE2 at which neonatal PML were slightly stimulated but the maternal cells were still suppressed. Preincubation for 18 h at 37 degrees C decreased the PGE2 induced suppression of the adult PML but did not change the response of the neonatal PML.