[The therapeutic effect of interferon-alpha exemplified by hairy cell leukemia]

Hairy cell leukemia (HCL) was one of the first malignancies in which therapy with natural interferon-alpha achieved complete remissions. In an early multicenter trial we could confirm the efficacy of IFN, especially of recombinant preparations. In more than 14 clinical studies using all types of IFN-alpha in dose ranges of 2.000,000 to 3.000,000 remission rates of 80 to 90% have been documented. The observation that interruption of IFN therapy may result in a relapse which responds again to IFN implies the need for continuous therapy with IFN at a low dose level in patients with HCL. Refractory relapses might respond to adenosine-desaminase-inhibitors. Own investigations show that the pancytopenia in HCL is a result of a lack of hematopoietic growth factors with a dominance of inhibitory factors such as TNF-alpha. Thus IFN therapy does not directly act on hairy cells but rather via influences on other cellular regulatory mechanisms.