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How do white blood cells fight infection

When the body is injured or infected, white blood cells pass through the walls of the capillary-blood vessels and congregate at the site of injury or infection.
Neutrophils and monocytes are both phagocytic, which means that they engulf and eat up invading bacteria and small particles, afterwards breaking up. Pus consists of an accumulation of dead neutrophils, monocytes, bacteria, and tissue.

• Lymphocytes, the major army group among white blood cells, are divided into several types:
• B cells, which produce chemical sub-stances called antibodies that attack specific viruses or bacteria;
• Helper and killer T cells, which produce other substances to fight off foreign organisms and even kill cells of the body already infected;
• Suppressor T cells, which slow down or stop the activities of B and other T cells after the infection has been eliminated; and
• Memory cells, which remember the invading organism for a long time to come, initiating a quicker response to subsequent infections. 

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