Concentrations of IL-10 in preterm human milk and in milk from mothers of infants with necrotizing enterocolitis

Background: Despite the protective effects of human milk against necrotizing enterocolitis, the incidence is highest in the extremely premature infant, and only minimally decreased with feeding human milk. This suggests that certain protective agents may be lower in milk from mothers delivering extremely premature infants. The anti-inflammatory cytokine IL-10 was one possibility. Aim: We hypothesized that low concentrations of IL-10 in preterm milk contribute to the development of necrotizing enterocolitis in extremely premature infants. Methods: IL-10 in human milk collected at weeks 1, 2, and 4 postpartum was measured by ELISA in mothers of infants born extremely premature at 23 - 27 wk gestation ( group EP), premature at 32 - 36 wk gestation ( group P), and term at 38 - 42 wk gestation ( group T). Single milk samples were collected from a separate group of mothers whose infants developed necrotizing enterocolitis. Results: There were no significant differences in concentrations of milk IL-10 among groups EP, P, or T. Concentrations of IL-10 declined as lactation progressed ( p < 0.001). IL-10 in milk was frequently undetected in all groups, but even more so in the milk of the group of women whose infants had necrotizing enterocolitis (86%) than in groups EP (40%) and P (27%) ( p < 0.01). Conclusion: IL-10 was present in preterm milk from most women, and the concentrations in preterm and term milk were not significantly different. A paucity of IL-10 in human milk was found in certain mothers in each group, especially in those whose infants developed necrotizing enterocolitis.