Cytokines and Endocrine Function

Abstract

Endocrine systems are influenced by a class of soluble mediators termed cytokines. These factors are glycoproteins ranging from 15,000–20,000 in molecular mass. Certain cytokines are also termed interleukins, denoting the importance of these proteins to the immune system. Interleukin-1 (IL-1) production by lymphocytes and monocytes affects inflammatory and cell-mediated immune responses. Although initially isolated from lymphocytes, many cytokines have been identified in other tissues. These proteins have a variety of functions depending on the tissue site of production. For example, IL-6 is a B-cell-differentiating and T-cell-activating cytokine. In addition, this protein enhances anterior pituitary hormone secretion and is produced within the anterior pituitary gland. This chapter will describe those cytokines that (1) affect endocrine functioning and (2) have sites of production within endocrine tissues. The cytokines most often associated with changes in endocrine function are IL-1, IL-2, IL-6, and tumor necrosis factor-α (TNF-α).