Abstract
Nosocomial sepsis in very low birth weight (VLBW) infants remains a major problem causing morbidity and mortality. Thus, the search of predictive markers for neonatal sepsis is mandatory. Regulatory T-cells (Treg) are a specialized thymus-derived T-cell subset involved in self-tolerance and suppression of effector responses.
Objective: To determine clinical and immunological markers predicting risk of nosocomial infection in VLBW.
Materials and methods: Inborn VLBW (< 1,500 g) were studied. Clinical parameters and peripheral blood immunophenotype by multi-parametric flow-cytometry (umbilical cord blood, UCB, at 7 days and at 1 month of life) were evaluated.
Results: 37 infants were included. Twenty-five (67%) infants developed nosocomial sepsis (day of onset, 9.9±3.4), and 3 died (12%). The only statistically significant clinical marker predictive of sepsis was gestational age, (p=0.005). No differences were observed in naïve, memory, pre-effector and/or effector CD4+ T-cells between those who developed sepsis and those who did not. In contrast, VLBW that developed sepsis exhibited higher Treg proportions (CD4+CD25+hi and CD4+CD25+FoxP3+) than those who not at birth (UCB, p=0.02 and p=0.29, respectively). A significantly higher expression of perforin on Treg was observed in VLBW that developped sepsis (p=0.05).
Conclusions: Expanded Treg in VLBW infants may reflect a physiologic developing immune system during tolerance learning. VLBW confront with pathogens and other stimuli at an early phase of thymic learning, which can interfere with effector immune responses against pathogens towards a tolerogenic response, and thus higher susceptibility to sepsis.
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Sánchez-Ramón, S., Sívori, C., Zamora, E. et al. 297 Expanded Circulating Regulatory T-Cells in Very Low Birth Weight Neonates: A Mechanism for Tolerance or a Threat for Sepsis?. Pediatr Res 68 (Suppl 1), 153 (2010). https://doi.org/10.1203/00006450-201011001-00297
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DOI: https://doi.org/10.1203/00006450-201011001-00297