Interferon and natural killer activity in multiple myeloma. Lack of correlation between interferon‐induced enhancement of natural killer activity and clinical response to human interferon‐α

Natural killer (NK) activity of peripheral lymphocytes was measured in 39 patients with multiple myeloma prior to and during interferon (IFN) therapy. NK activity increased in a majority of patients following the first injection of IFN and remained at an increased level during 1 year of therapy. Lower doses of IFN seemed to induce a greater increase in NK activity than higher doses. No correlations could be observed between the response of the tumors to IFN therapy and pretreatment levels of NK activity, IFN-induced enhancement of NK activity in vitro or IFN-induced enhancement of NK activity in vivo.