The relationship between interleukin-6 and herpes simplex virus type 1: Implications for behavior and immunopathology

Cytokines are hormones once thought to be restricted to the immune system p roduced solely by hematopoietic-derived cells and acting on receptors expre ssed by cells of the immune system. However, it is now clear that many cyto kines are produced not only by lymphocytes, monocytes, granulocytes, and de ndritic cells but are also synthesized by cells outside the realm of the im mune system in response to stimuli that may not be associated with immune h omeostasis. In fact, there is evidence supporting a role of selected cytoki nes modifying behavior and neuroendocrine function. Recently, a potential r elationship between the cytokine interleukin (IL)-6 and herpes simplex viru s type 1 (HSV-1) reactivation has been found. This article discusses the re levance of these findings and considers the potential impact that HSV-1 inf ection has on behavior and chronic inflammatory processes that can occur in the nervous system during "latent" virus infection as a result of chronic IL-6 expression. (C) 1999 Academic Press.