Elevated body temperature in a patient with infection is often due to the action of which substances?

Elevated body temperature, commonly referred to as fever, in a patient with an infection is primarily due to the action of pyrogens. Pyrogens are substances that induce fever by acting on the hypothalamus, the part of the brain responsible for regulating body temperature. When an infection occurs, the immune system releases these pyrogens, which can be either endogenous (produced by the body) or exogenous (derived from outside the body, such as from bacteria).

Endotoxins, which are components of the outer membrane of certain bacteria, can certainly trigger the release of endogenous pyrogens, but they are not the direct cause of elevated temperature. Exosomes are small vesicles involved in intercellular communication but do not have a direct role in fever response. Interferons are cytokines that play a critical role in the immune response to viral infections but do not directly cause an increase in body temperature like pyrogens do.

This understanding of pyrogens and their role in fever helps clarify why they are central to the response to infections, highlighting their importance in the immune system's attempt to fight off pathogens.