Interleukin-12: potential clinical applications in the treatment of chronic viral hepatitis.

Interleukin-12 (IL-12) is a heterodimeric cytokine that promotes cell-mediated immunity by facilitating type 1 helper T-lymphocyte responses, inducing the secretion of interferon-gamma from both T and natural killer cells, enhancing the lytic activity of natural killer cells, and augmenting specific cytolytic T-lymphocyte responses. In addition, IL-12 can increase the production of some subclasses of IgG antibodies. IL-12 has been shown to have potent therapeutic effects in a number of animal models of tumours and infectious diseases, including several viral infections. These results have led to the initiation of clinical trials to evaluate the therapeutic potential of IL-12 in human cancer patients and in patients infected with the human immunodeficiency virus. The biological activities of IL-12 suggest that it may also have clinical utility in the treatment of patients suffering from chronic hepatitis B or C virus infections. Because of the lack of suitable animal models for evaluating the efficacy of IL-12 in the treatment of infections with these viruses, only a clinical trial in patients with chronic viral hepatitis can address the potential role of IL-12 as an effective treatment for these disorders.