Neutrophils have been implicated in the pathogenenesis of a variety of inflammatory diseases including the adult respiratory distress syndrome, idiopathic pulmonary fibrosis, ulcerative colitis and rheumatoid arthritis. Although the neutrophil is a vital component of the body's defense against infectious agents, uncontrolled release of its toxic substances may inflict "friendly fire" damage on surrounding tissue and propagate the inflammatory response, leading to scarring and tissue destruction. Apoptosis leads to recognition and safe disposal of dying cells by phagocytosis.