What is the primary function of white blood cells?

The primary function of white blood cells is to fight infection. White blood cells, or leukocytes, are key components of the immune system that work to identify, target, and eliminate pathogens such as bacteria, viruses, and other foreign substances that can cause disease. They are produced in the bone marrow and are essential for the body's defense mechanisms. When an infection occurs, the number of white blood cells typically increases as they respond to the threat, often moving to the site of infection to perform their functions, which include phagocytosis (engulfing and destroying pathogens), producing antibodies, and releasing substances that help regulate the immune response. This capability makes them vital for maintaining health and resisting infections.