850 The Expression of Pro-Inflammatory Cytokine Il-17 in Neonates

Introduction: Neonates, and more so preterms, are known to have deficient adaptive immune responses, critical for host defense mechanisms against pathogens. Adaptive immune responses are mediated by the activation of pathogen-specific T helper type 1 (Th1), Th2 lymphocytes and, the recently indentified, Th17 cells. Th17 lymphocytes produce the pro-inflammatory cytokine IL-17 which provides protection against mainly extra-cellular pathogen infections. However IL-17 release has been hardly studied in neonates. The aim of our study was to investigate the expressions of IL-17 in the serum of term and preterm newborns and compare them to those of adults. Patients and methods: Thirteen (13) healthy preterm neonates [birth weight (BW): 1740g (1500-2200), gestational age (GA): 32,5wk (31-34)] and 13 healthy term neonates [(BW: 2960g (2500-4310), GA: 37,5wk (37-39)] were studied. Six (6) healthy adults were used as controls. Peripheral blood samples were obtained from neonates during the 2nd and 3rd weeks of life. IL-17 levels were measured in the serum by ELISA. Results: Serum IL-17 levels did not differ between preterm and term neonates. However, IL-17 levels were significantly lower in both preterm and term neonates, as compared to those of adults (p > 0,001 for both terms and preterms). Conclusion: Our data reveal dramatically decreased IL-17 release in the serum of neonates compared to adults, mirroring the immaturity of the neonatal immune responses. Importantly, our findings suggest that deficient IL-17 release in neonates may hamper their host defense against extracellular pathogens often leading to overwhelming septicemia and death.