Therapeutic leukapheresis in hairy cell leukemia.
Therapeutic leukapheresis was performed on three patients, and plasmapheresis on two patients with far-advanced hairy cell leukemia. Two of the three patients who were treated with leukapheresis had many hairy cells in their peripheral blood, while the other had relatively few. In each patient, dramatic clinical and hematologic improvements were observed that have sustained for more than 23, 10, and 26 months, respectively. Plasmapheresis of similar intensity failed to show any appreciable therapeutic effects on two other patients with similar clinical and hematologic findings. We believe that the favorable therapeutic effects of leukapheresis are due to the removal of factors capable of inhibiting normal hematopoiesis. This factor(s) is present in the cells that were removed by leukapheresis. The exact nature of this factor(s) or the cells that produce this factor(s) remains to be identified.