Neutrophils play a key role in nutritional immunity because they constitute the largest proportion of circulating white blood cells in humans, quickly mobilize to sites of infection, and express high levels of antimicrobial proteins that sequester metal ions, including lipocalin-2, lactoferrin, and, as detailed below, calprotectin (Masson et al., 1969; Steinbakk et al., 1990; Goetz et al., 2002). This evidence concerns the gene LCN2 and infection.