NEUTRALIZING 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 interfero n alpha(2b) (IFN-alpha(2b)) as maintenance therapy for multiple myelom a, antibodies were detected in 58% (17/29) of patients measured by a s olid-phase enzyme-linked immunosorbent assay (ELISA). Only 7/17 patien ts who were positive for antibody in the ELISA had neutralising antibo dy to IFN-alpha(2b), measured by virus growth inhibition. These patien ts comprised six who were receiving IFN-alpha(2b) at the time of asses sment and one who had finished treatment. Among patients who were rece iving 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. T wo patients who were positive for neutralising antibody remain in remi ssion 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 ser um from six normal donors. The data suggest that neutralising antibody formation in patients with multiple myeloma is not responsible for re lapse in patients receiving IFN-alpha(2b). The transient nature of neu tralising antibody production in patients who remain in remission sugg ests that this response to IFN-alpha(2b) is not associated with memory B cells.