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Why does pus often form at sites of acute inflammation?

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Tuberculosis — disease A doctor examining chest X-rays of patients infected with tuberculosis, which remains one of the world's deadliest diseases.

Pus forms at sites of acute inflammation primarily through a process called suppuration, which occurs when the body struggles to eliminate an inflammatory agent, such as a bacterial infection.1

During the inflammatory response, neutrophils—a type of white blood cell—migrate in massive numbers from the bloodstream to the site of injury to ingest and destroy invading bacteria. Because these neutrophils have a short life span, they die in great numbers after completing their mission.23

Pus is the resulting viscous, opaque fluid composed of these dead and dying neutrophils, cellular debris, bacteria, and fluid that has leaked from blood vessels. If this accumulation becomes walled off by a membrane, it forms an abscess, which can be difficult to treat because it is often inaccessible to antibodies and antibiotics.142