Basic problem and objective: Autoimmunity may occur in chronic hepatitis C (CHC) as a primary event or may be induced by interferon-alpha (IFN-alpha). The existence of autoantibodies (AAB) is considered to be a contraindication to interferon treatment. It was the aim of this study to determine the extent to which signs of autoimmune disease occur in the treatment of CHC with interferon, even in patients with existing antibodies.
Patients and methods: In 1994 a pre-defined AAB spectrum and thyroid function parameters were determined every other month in 41 patients with CHC (16 women, 25 men; median age 42 years) before and after they had been treated with IFN-alpha, even when AABs were already present.
Results: AABs were demonstrated in 17 patients (41%) before and in 26 (63%) during interferon treatment (P = 0.001). In 13 patients new AABs were demonstrated, while previously present AABs were no longer found in four patients. AABs against thyroglobulin (TGA) increased significantly, during interferon treatment (P = 0.001). All except thyroid AABs were demonstrable only at times and in low titres. None of the patients had an auto-immune disease before treatment. But autoimmune thyroiditis developed in four of 19 patients with thyroid AABs. These patients also had constant TGAs in high titres, and antibodies against microsomes were additionally demonstrated in two. No other autoimmune disease occurred during or after interferon treatment.
Conclusion: Interferon frequently induces the formation of AABs. The demonstration of AABs before or during interferon treatment is no contraindication to it, with the exception of preexisting thyroid antibodies, which indicate a high risk of autoimmune thyroiditis.