Phagocytic white blood cell engulfing a bacterial cell, computer artwork. Phagocytic blood cells such as neutrophils and macrophages ingest and destroy pathogens, dead cells and cellular debris, and form an important part of the body's immune system. When a phagocyte comes into contact with a bacterium, receptors on the phagocyte's surface bind to the bacterial cell. This stimulates the phagocyte to engulf and destroy the bacterium. Highly mobile, phagocytic cells migrate to areas of tissue damage. However, their enzymes are quickly depleted by phagocytic activity so they degenerate. Defunct cells accumulate in pus.