Phagocytic activities in neonatal monocytes.

Monocytes play an essential role in cellular host defense as circulating phagocytes, as well as precursors of macrophages. We investigated the principal phagocytic activities in monocytes from cord blood of term infants by analysing adherence, random migration, chemotaxis, bactericidal activity, phagocytosis-associated chemiluminescence, production of superoxide anion (O-2) and generation of hydrogen peroxide (H2O2). All phagocytic functions of monocytes from neonates were shown quantitatively to be comparable to those of cells from healthy adult volunteers. The increased susceptibility of the human neonate to serious systemic infections cannot be related to an abnormality in monocyte function.