Mechanism of fever

Mechanism of fever

In this graphic, the mechanism of fever caused by an inflammatory reaction is explained. The bacteria produce endotoxins, which trigger cells of the immune system (monocytes, granolocytes and macrophages) to produce endogenous pyrogens. Endotoxins are exogenous pyrogens. Endogenous pyrogens are cytokines like interleukine (IL)-1 and IL-6, tumor necrosis factor (TNF) and interferon (INF)-α.

Both groups of pyrogens stimulate the synthesis of prostaglandins, the actual compounds that increase the thermostat set point. The synthesis begins with the conversion of a phospholipid of the cell membrane into arachidonic acid (AA) by the enzyme phospholipase A2. The second step is the conversion into prostaglandin by the enzyme cyclo-oxygenase (COX).


Aspirin and other drugs that inhibit the synthesis of prostaglandins, reduce fever. 


Aspirin given to a healthy person reduces the body temperature.