Monocyte-macrophage function in the newborn.

Analysis of 20 human cord blood samples for monocyte-macrophage function demonstrates a selective defect in monocyte cellular chemotaxis. Monocyte bacterial phagocytosis, phagocytosis of paraffin oil particles, and bacterial killing of staphylococcus 502A were normal when compared with 30 healthy young adult controls. Impaired response of neonatal monocytes to chemotactants is an additional host defense defect that may help explain the undue susceptibility of neonates to certain infectious agents.