Effect of interferon-alpha therapy on bone marrow fibrosis in chronic myelogenous leukemia

The aim of this study was to investigate the influence of interferon-alpha (IFN-α) on bone marrow fibrosis associated with chronic myelogenous leukemia (CML). Eighty-two bone marrow biopsies from 41 patients in chronic phase CML were stained with Snook's reticulin stain for argyrophilic fibers. Grading of reticulin fibrosis (scale of 1 to 4) was according to the quantity and pattern of distribution of reticulin. The interval between biopsies was a median of 25 months (range 12 to 40 months). Patients had been treated with IFN-α for at least 12 months, were still on IFN-α therapy during the study, and had achieved at least a complete hematological response. Before the start of IFN-α therapy, reticulin fibrosis was grade 1-2 in 23 patients (56%) and grade 3-4 in 18 (44%). During IFN-α therapy, reticulin fibrosis in bone marrow did not worsen or was reduced in 33 patients (80%) and increased by one grade in eight patients (20%). Only five patients (12%) with limited fibrosis (grade 1-2) before start of IFN-α therapy showed an increase towards significant fibrosis (grade 3-4), while eight of the 18 patients (44%) with grade 3-4 fibrosis achieved a decrease of fiber content in bone marrow. In summary, IFN-α was not associated with an enhancing effect on myelofibrosis in patients with CML and may have prevented increasing fibrosis in patients who respond to therapy.