Neutrophil leukocytes contain primary and secondary granules with enclosed antimicrobial proteins, peptides, and enzymes, such as lactoferrin, defensins, bactericidal/permeability-increasing protein (BPI), azurocidin/heparin-binding protein, cathelicidins, phospholipases A2, calprotectin, etc. After activated neutrophils migrate to the site of infection, pathogens are exposed to released antimicrobial substances either in the phagosome or extracellularly [64]. Here, BPI is linked to infection.