Biochemical and immunological responses of hairy cell leukemia patients to interferon beta.

Ten hairy-cell leukemia patients were treated with interferon beta (IFN-beta) at a dose rate of 2 x 10(6) IU/m2 x 5 days for 4 weeks (induction therapy) and, thereafter, at the same dose three times a week for 11 months (maintenance therapy). The effect of this treatment on serum neopterin, beta-2-microglobulin, (2'-5')oligoadenylate [(2'-5')A(n)] levels, intracellular (2'-5')A(n) values and human Mx protein synthesis was analysed. There were significant rises in serum neopterin and (2'-5')A(n) levels during both induction and maintenance, whereas beta-2-microglobulin levels rose only during induction. Rises in intracellular (2'-5')A(n) were documented mainly during induction, but they were not significantly higher than pretherapy values. IFN-beta provoked an increase in human Mx protein synthesis over the entire induction-maintenance period, but was only significantly higher than baseline during induction. All markers proved useful for monitoring the effects of IFN-beta dose schedules, but were not predictive of clinical outcome. Natural killer activity and IFN-gamma production, which were initially defective, followed a different trend from that of the other factors studied, in that increases were documented only late in the course of therapy when the disease was already in remission.