Recombinant human interleukin-6: safety issues of a pleiotropic growth factor.

Interleukin-6 (IL-6) plays a pivotal role in hematopoiesis, immune reactions and acute phase responses. It has been demonstrated, however, that the abnormal expression and dysregulation of IL-6 homeostasis are involved in the pathogenesis of a range of diseases. It is the purpose of this article to review briefly some of the biological properties of IL-6 in order to discuss issues related to the safety evaluation of recombinant human IL-6 (rhIL-6). Knowledge of the biological properties is important for, (1) selection of a responsive species for toxicological studies and (2) proper interpretation of the side-effect profile.