Explain Pus Formation

Once a neutrophil finds a foreign particle or a bacterium, it will engulf it releasing enzymes, hydrogen peroxide and other chemicals from its granules to kill the bacteria. In a site of serious infection (where lots of bacteria have reproduced in the area), pus will form. Pus is simply dead neutrophils and other cellular debris. Many neutrophils and macrophages are killed by toxins released by highly virulent invaders. The dead phagocytes, microbes are trapped by still bigger phagocytes and they form a protective barrier. Dead phagocytes, enzymes, fluid, protein, damaged tissue cells etc. leak from capillaries and leave the body in the form of pus. This is a sure sign of infection. Like pus, fever too is a defence mechanism.