INTERLEUKIN-2-ALPHA AND INTERFERON-ALPHA INDUCED NATURAL-KILLER-CELL ACTIVITY AS A MARKER OF PROGRESSION IN HAIRY-CELL LEUKEMIA

Hairy cell leukemia (HCL), a rare B-cell chronic lymphoproliferative d isorder, is often accompanied by immune abnormalities. A marked impair ment of the natural killer cell-mediated cytotoxity (NK activity) has been reported in most patients at diagnosis. In the present report a l ong-term follow-up study of NK activity of splenectomized HCL patients is recorded. Among patients who persisted with stable disease two gro ups, one with normal NK activity, and another with low NK activity, co uld be recognized. Patients with progressive stage were characterized by a low NK cytotoxic activity. In vitro tests showed that interferon alpha (IFN-alpha) and interleukin 2 (IL2) could increase the NK activi ty to normal levels only in HCL patients with stable disease, while in progressive HCL these cytokines showed a significantly decreased effe ct. These results indicate that cytokine-induced NK cytotoxicity appea rs to be a valuable parameter in assessing the stage of HCL.