Early response to alpha interferon in a patient affected by hairy cell leukemia.

A 61-year-old splenectomized male patient affected by hairy cell leukemia (HCL) in relapse was treated with interferon (IFN) at a dosage of 3 x 10(6) U/day. After only 11 days of treatment, IFN was stopped because the patient developed fever, jaundice and respiratory distress. Upon recovery from this infectious episode, the patient was judged to be in complete remission of HCL on the basis of clinical and laboratory findings, and he remained off-therapy for 2 years. When an overt relapse occurred, the patient was again treated with IFN and, after a very short time, he achieved a new, good partial remission that is maintained 28 months later without treatment. This observation remains speculative for understanding the mechanism of action of IFN in other comparable HCL cases.