Synthesis of interleukin 1/endogenous pyrogen in the brain of endotoxin-treated mice: a step in fever induction?

Abstract

The brain may be an immunologically privileged site, in that it lacks lymphatic drainage and is shielded from the immune system by the blood brain barrier. However, astrocytes were recently discovered to present antigen to T cells, to express class II antigens of the major histocompatibility antigen complex, and to release interleukin 1- (IL 1) like factors in vitro. Recent reports reveal similarities between macrophage-derived IL 1 with the fever inducer endogenous pyrogen (EP) 3; so IL 1 secreted by astrocytes may also play a key role in temperature regulation. In general, fever induction is thought to be mediated by circulating IL 1/EP gaining access to thermoregulatory centers of the hypothalamus. Another pathway of fever induction is shown here by the demonstration of synthesis of IL 1/EP within the brain of mice injected i.p. with endotoxin.