Cytokine-induced autoimmune disorders

Cytokines are now commonly used in the treatment of many conditions, especially cancer, haematological malignancies and chronic viral hepatitis. With some of these cytokines, clinical induction and/or exacerbation of autoimmune manifestations have been observed. This has been the case with interferon-a and interferon-gamma, interleukin-2 and some colony-stimulating factors. All known biological and clinical autoimmune features have been observed but thyroid abnormalities have been particularly frequent. Same of these manifestations appear to be related to the effect of these exogenous cytokines on the T helper cell (T-H) 1/T(H)2-cytokine balance and the regulatory properties of these cells. Patients with a history of underlying autoimmune disease or baseline serological abnormalities should be monitored for autoimmunity when treated with certain T(H)1 or T(H)2-inducing cytokines. Cytokines are now used in the treatment of an increasing number of diseases. This has been possible because of rapid progress in the discovery of different cytokines and in the biotechnology techniques allowing their production to be of high quantity and purity. In the early stares of the development of cytokine treatment. diseases were selected as targets based on the limitations of current treatment rather than a scientific rationale. Thus, cancer and haematological malignancies were selected first. Unpredicted adverse effects were observed. Indeed, the therapeutic administration of cytokines has assisted in clarifying some concepts regarding their role in host defence. In a number of cases. autoimmunity was detected. With time, the situation has been clarified and various explanations for this observation have emerged. In particular, the classification of cytokines according to their regulatory properties has been useful to explain some of these manifestations.