Evaluation of the basic mechanisms of activation via Toll-like receptor 4 (TLR-4) in monocytes from term and preterm newborns

A imaturidade do sistema imune adaptativo ao nascimento envolve alterações funcionais das células apresentadoras de antígenos. O objetivo foi avaliar a ativação via TLR-4 e resposta de monócitos de sangue de cordão umbilical de recém-nascidos (RN) pré-termo ³34 e ³34 and < 37 weeks (Group 2) and term NB (Group 3). The results show high production of IL-8, TNF-a, IL-1b and IL-6 and a significantly lower production of IL-10 by neonatal monocytes. NF-kB factor presented similar activation among neonates and adults. p38, ERK-1/2 and IRAK-4 molecules were more activated in monocytes of newborns from Group 1 as compared to newborns from Group 3 and adults. The phagocytic ability of monocytes and neutrophils from newborns showed a reduced competence. The H2O2 production was reduced in monocytes and neutrophils only in preterm newborns. The results suggest a functionally distinct neonatal immune profile, revealing an imbalance of the innate immune response, with a lower efficiency in the control of this response, which could lead to a predisposition to sepsis.