Effects of Group B Streptococci on Cord and Adult Mononuclear Cell Interleukin-12 and Interferon-γ mRNA Accumulation and Protein Secretion

Group B streptococci (GBS) are a major cause of early-onset infection in neonates. Neonates, who have defects in neutrophil function that likely contribute to susceptibility to GBS infection, are deficient in the production of the phagocyte activator interferon (IFN)—γ. GBS-stimulated mRNA accumulation and protein secretion of IFN-γ and interleukin (IL)—12, a major enhancer of IFN-γ production, by mixed mononuclear cells (MMCs) from umbilical cord and adult peripheral blood was examined. GBS-exposed cord blood MMCs secreted lower concentrations of both IL-12 and IFN-γ proteins than did MMCs from adults. IL-12 and IFN-γ mRNA accumulation was examined by use of comparative reverse transcriptase—polymerase chain reaction. Cord blood MMCs accumulated less mRNA for both IL-12 and IFN-γ than did adult blood MMC. The deficiency in cord blood cell production of IL-12 may have a role in inadequate IFN-γ production, which contributes to the unique susceptibility of neonates to GBS infections.