Bacterial phagocytosis by macrophages. Time-lapse light microscopy footage of bacterial phagocytosis by macrophages. Macrophages are cells of the body's immune system. They phagocytose and destroy pathogens, dead cells and cellular debris. Here, the macrophages (larger objects) are engulfing the bacteria (smaller, dark blue rods), a process known as phagocytosis. The bacteria will then be destroyed.