Pyrogen

A Pyrogen is a substance, typically produced by a bacteria, that can cause a rise in body temperature. Pyrogens can be either exogenous or endogenous. Exogenous pyrogens are external to the body, often bacterial in origin, while endogenous pyrogens are produced by the body, typically in response to an infection or tissue damage.

Types of Pyrogens

Exogenous Pyrogens

Exogenous pyrogens are often bacterial products such as lipopolysaccharides (LPS). These substances can stimulate the body's immune cells to release substances that can affect the hypothalamus and raise body temperature.

Endogenous Pyrogens

Endogenous pyrogens are typically produced by the body's own immune cells in response to an infection or tissue damage. These include substances such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF).

Effects of Pyrogens

When pyrogens bind to certain receptors in the body, they can trigger a cascade of events leading to a rise in body temperature. This is often part of the body's defense mechanism against infection, as the raised temperature can help to kill off invading pathogens.

Detection and Removal

Pyrogens can be detected in a variety of ways, including the Limulus amebocyte lysate (LAL) test, which uses blood from the horseshoe crab to detect bacterial endotoxins. Pyrogens can be removed from substances such as drugs and vaccines through a process known as depoyrogenation.

See Also

• Fever
• Inflammation
• Sepsis