Skin—the first line of defense

      Skin is an organ. This is widely appreciated by neonatologists and pediatricians alike who recognize the importance of skin as a barrier to loss of fluid and electrolytes. In this issue of The Journal, Walker et al demonstrate an additional role of the skin in protecting the infant from infection. Using a novel approach to sample skin cells and protein contained within the surface layers of the skin, the authors identified several important host defense proteins in the skin of term newborns. Proteins were identified by Western blot and enzyme activity by specific assays. Lysozyme and lactoferrin were detected in the proteins extracted from “sampled skin” of both newborns and adults. Importantly, the concentration and enzymatic activity was greater in cells extracted from newborn skin than from adult. The presence of these factors in the skin of the newborn is likely to contribute importantly to the newborn infant's defense against invasive bacterial infections. Future studies will compare the expression of these proteins and enzymatic activities in infants of different gestational ages and their relationship to the risk of nosocomial infection. Moreover, care strategies which complement the expression of these host defense proteins in skin could provide an adjunctive approach to reduction of nosocomial infections in the newborn.