title: High level interleukin-12 production, but diminished interferon-gamma production, by cord blood mononuclear cells.
abstract: Cell-mediated immunity (CMI) in neonates is relatively deficient when compared with adults. Defects in cytokine production and/or regulation may contribute to heightened susceptibility to infection by intracellular pathogens. The heterodimeric cytokine IL-12 is a key regulator of CMI and inducer of interferon-gamma (IFN-gamma) production. We report here that umbilical cord blood-derived mononuclear cells (MNC) are capable of producing IL-12 (p40 subunit, measured by RIA, and IL-12 p70 heterodimer, by ELISA) at levels comparable to or greater than adult peripheral blood MNC, after stimulation with heat-killed Staphylococcus aureus in 18-h cultures. As in adult MNC, S. aureus induced IL-12 p40 mRNA accumulation in cord blood MNC. IFN-gamma was also produced in the S. aureus-stimulated cultures, in an IL-12-dependent manner, but cord blood MNC produced 5-fold lower levels of IFN-gamma compared with adult MNC (p < 0.05). Preincubation with IL-10 inhibited IL-12 p40 production by cord blood and adult peripheral blood MNC in a dose-dependent fashion, whereas neutralization of endogenous IL-10 enhanced IL-12 and IFN-gamma levels. The results demonstrate that the relative CMI deficiency in neonates is not due to an intrinsic defect in the capacity of neonatal MNC to produce IL-12. The underlying factors responsible for diminished IFN-gamma production are not known, but may lie in the balance of stimulatory and inhibitory signals delivered to the IFN-gamma secreting cells along with IL-12, or may relate more to the absence of memory T cells among cord blood MNC.
authors.affiliation: Department of Pediatrics, University of California, San Francisco 94143, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Scott
authors.forename: M
authors.initials: M
authors.lastname: Kubin
authors.forename: S
authors.initials: S
authors.lastname: Kohl
mesh_terms: D005312:Fetal Blood / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007111:Immunity, Cellular; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000096:biosynthesis*; D016753:Interleukin-10 / Q000494:pharmacology; D018664:Interleukin-12 / Q000096:biosynthesis* / Q000737:chemistry; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D010446:Peptide Fragments / Q000096:biosynthesis*; D013211:Staphylococcus aureus / Q000502:physiology
chemical_list: D010446:Peptide Fragments; D016753:Interleukin-10; D018664:Interleukin-12; D007371:Interferon-gamma