Objective. The mechanisms by which newborns are at increased risk for invasive bacterial
infections have been incompletely defined. A central element of innate immunity to bacterial
infection is the neutrophil—a cell that contains cytoplasmic granules replete with antibiotic
proteins and peptides. The activity of adult neutrophils against Gram-negative bacteria is
believed to depend to a significant degree on the presence in neutrophil primary
(azurophilic) granules of the 55-kDa bactericidal/permeability-increasing protein (BPI) …