Neutralising antibodies in patients with multiple myeloma receiving maintenance therapy with interferon alpha 2b.

In a study of 29 patients who were receiving or had received interferon alpha 2b (IFN-alpha 2b) as maintenance therapy for multiple myeloma, antibodies were detected in 58% (17/29) of patients measured by a solid-phase enzyme-linked immunosorbent assay (ELISA). Only 7/17 patients who were positive for antibody in the ELISA had neutralising antibody to IFN-alpha 2b, measured by virus growth inhibition. These patients comprised six who were receiving IFN-alpha 2b at the time of assessment and one who had finished treatment. Among patients who were receiving the cytokine, four had progressive disease, one was in complete remission and one in partial remission. Neutralising activity was also detected to natural human leucocyte IFN-alpha in the same patients. Two patients who were positive for neutralising antibody remain in remission and are continuing to receive IFN-alpha 2b. These two patients have since lost their neutralising titre. No neutralising antibody to IFN-alpha 2b or natural human leucocyte IFN-alpha was detected in serum from six normal donors. The data suggest that neutralising antibody formation in patients with multiple myeloma is not responsible for relapse in patients receiving IFN-alpha 2b. The transient nature of neutralising antibody production in patients who remain in remission suggests that this response to IFN-alpha 2b is not associated with memory B cells.