Serum anti-interferon alpha antibodies in chronic hepatitis C patients treated with pegylated interferon alpha containing therapy

The development of anti-IFN? antibodies is an occurrence described in chronic hepatitis C patients during treatment with Interferon?/PEG-Interferon?. However, its relevance, especially in difficult-to treat patients, has not been defined. Methods: We retrospectively measured the serum levels of anti-IFN? antibodies (baseline and week 12) and IFN? levels (week 12) by ELISA in 76 previous non-responders, and in 14 naive patients treated with Pegylated-IFN? and Ribavirin. A group of 57 healthy donors (HD) was also assessed as control. Positivity to anti-IFN? antibodies was established on the values of HD. Results: Baseline anti-IFN? antibodies were detected in 15.5% of patients and in 7% of HD, with significantly higher concentrations in patients than HD (181.5à,±389.9 vs 95.9à,±143.0 ng mL?1, p=0.0023). All positive patients were IFN?-experienced. At week 12, the prevalence of positivity increased to 22.3 and 28.5% in experienced and naàƒ¯ve patients, respectively, and the levels of anti-IFN? antibodies did not differ between the two groups (391à,±792.3 vs 384.7à,±662.6 ng mL?1, respectively). IFN? concentrations were significantly lower in antibody-positive patients than in antibody-negatives (988.2à,±1402 vs 3462à,±830.8 pg mL?1, p?0.0001) and the levels of antibodies and IFN? were inversely correlated (r=-0.405, p=0.0001). The antibody-positive population clustered in null responders (67%) and 19/21 patients (90%) did not achieve SVR. Conclusions: The development of anti-IFN? antibodies is a non-negligible occurrence in patients treated with PEG-IFN?, is stable over time, and has a relevant clinical impact when associated with low levels of circulating PEG-IFN?. It should be considered in patients undergoing treatments including PEG-IFN?.