Perinatal influences on in vitro B lymphocyte differentiation in human neonates.

In vitro differentiation of B lymphocytes present in cord blood mononuclear cell preparations into immunoglobulin secreting cells was studied in 126 neonates with gestational ages (GA) ranging from 20 to 44 wk. Eight infants had a GA less than 27.9 wk, 24 had GA 28-32.9 wk, 30 had GA 33-37.9 wk, 51 had GA 38-41.9 wk, and 13 had GA above 42 wk. B cell differentiation in response to pokeweed mitogen plus hydrocortisone was assessed using a plaque forming cell assay. All neonates had a measurable plaque-forming cell response in this assay. An increased plaque-forming cell response was observed in some neonates in all gestational age groups. The magnitude of in vitro neonatal B cell differentiation underwent a continuous and significant (p less than 0.002) reduction as gestational age increased. The influence of intrauterine growth retardation on in vitro B lymphocyte differentiation was studied and compared to gestational age-matched controls with a normal intrauterine growth. Intrauterine growth retardation was not associated with changes in B cell responsiveness. An analysis of perinatal factors revealed that cesarean section, and low 1-min Apgar scores were factors that predisposed cord blood cells to be triggered in vitro to produce increased numbers of plaque-forming cells.