protein and polysaccharide substances called pyrogens, released either from bacteria or viruses or from destroyed cells of the body, are capable of raising the thermostat and causing a rise in body temperature. Fever is a highly significant indicator of disease.

What are the sources of pyrogens?

Their main sources are Gram-negative and Gram- positive bacteria, fungi, viruses and several non-microbial substances [2,7,8]. The most potent, widely known and well characterized pyrogens are endotoxins which are derived from dead or living Gram-negative bacteria [9].

Do macrophages produce pyrogens?

Feeding macrophages release additional chemical signals called pyrogens. Pyrogens circulate to the brain via the blood and cause it to increase body temperature. The resulting fever tends to accelerate the activity of white blood cells and can also decrease the growth of invading cells.