Immune response

Innate immunity; Humoral immunity; Cellular immunity; Immunity; Inflammatory response; Acquired (adaptive) immunity

The immune response is how your body recognizes and defends itself against bacteria, viruses, and substances that appear foreign and harmful.

Immune system structures

The immune system protects the body from potentially harmful substances. The inflammatory response (inflammation) is part of innate immunity. It occurs when tissues are injured by bacteria, trauma, toxins, heat or any other cause.


The chemicals also attract white blood cells that eat microorganisms and dead or damaged cells. The process where these white blood cells surround, engulf, and destroy foreign substances is called phagocytosis, and the cells are collectively referred to as phagocytes. Phagocytes eventually die. Pus is formed from a collection of dead tissue, dead bacteria, and live and dead phagocytes.