Activity of B-cell lineage system in the cord blood of newborns.

To evaluate the B cell lineage system in newborns we estimated IL-4 (BCGF/BSF-1) production by lymphocytes isolated from the cord blood and its influence on antibody synthesis. Undertaken experiments were performed in two groups of newborns: stressed newborns mainly with perinatal infection and full-term healthy neonates, comparing to peripheral blood of adults as control. Results revealed 1) the significantly higher percentage of mature B cells (B1) in cord blood of stressed newborns, 2) the significantly higher IL-4 production comparing to full-term neonates, 3) diminished IgG and IgA synthesis in vitro by allogenic activated B cell blasts in the presence of supernatants from cultures of PHA-stimulated lymphocytes isolated from cord blood of stressed newborns. Induction of IgM synthesis by these active supernatants was significantly higher in stressed newborns than in the other examined groups. We suggest that immunoregulatory mechanisms, which control the production of IL-6 (BCDF/BSF-2) are still not completely mature at birth.