Azurocidin also known as cationic antimicrobial protein CAP37 or heparin-binding protein (HBP) is a protein that in humans is encoded by the AZU1 gene. Azurophil granules, specialized lysosomes of the neutrophil, contain at least 10 proteins implicated in the killing of microorganisms. The protein encoded by this gene is an azurophil granule antimicrobial protein, with monocyte chemotactic and antibacterial activity. It is also an important multifunctional inflammatory mediator. In patients with fever, high plasma levels of HBP indicates that the patient is at high risk of developing sepsis with circulatory collapse.