IMMUNOLOGICAL ADVERSE-EFFECTS OF INTERFERON TREATMENT

The immunological adverse effects of interferon treatment have become a matter of concern because of the widespread use of these agents. Interferons have various and profound effects on the immune system, such as modulation of immunoglobulin synthesis, T cell-mediated cytotoxicity and natural killer cell activity, and enhancement of the expression of major histocompatibility complex molecules. The major immunological adverse effects of interferons are aggravation of pre-existing autoimmune disorders, unmasking of silent autoimmune processes and induction of de novo autoimmunity. The possible development of almost all the organ-specific and nonspecific autoimmune diseases involving autoantibodies should be taken into account in interferon treatment. Thyroid autoimmune disorders are most frequently observed. Autoimmune complications induced by interferon are usually reversible by cessation of interferon treatment alone or by the additional administration of immunosuppressive treatment. However, some possible complications of interferon therapy, especially systemic lupus erythematosus and interstitial pneumonitis, should be recognised as life-threatening, and even fatal. Allograft rejection in patients with liver or kidney transplants, and graft-versus-host disease in patients treated with bone marrow transplants, may develop following interferon treatment, Furthermore, contrary to the inhibitory effects of interferons on tumour growth, development of lymphoproliferative and myeloproliferative disorders, including plasma cell and myeloid leukaemia, and enhancement of metastases of malignant melanoma have also been observed. Finally, the emergence of anti-interferon antibodies may lead to loss of therapeutic activity and the requirement To employ another interferon preparation.