Cytogenetic remissions induced by interferon alpha and imatinib mesylate are immunologically distinct in chronic myeloid leukemia.

We compared immunologic parameters of chronic myeloid leukemia (CML) patients in cytogenetic remission receiving imatinib mesylate (STI) treatment, CML patients receiving interferon alpha (IFN-alpha), and healthy volunteers. Each group comprised 14 subjects. Median treatment dosages and durations were 6 x 10(6) IU/week and 174 months, respectively, for IFN-alpha and 400 mg/day and 54 months for STI. The numbers of T-cells were significantly lower in the 2 patient groups (P = .0006), whereas the 3 groups were comparable with respect to the numbers of natural killer cells. Not only the absolute numbers of monocytes and B-cells but also serum immunoglobulin G (IgG) and IgA titers were significantly lower in the STI group than in the IFN-alpha group (P < .0001). For T-cell subsets, the ratio of CD4 T-cells to CD8 T-cells was significantly lower in the IFN-alpha group than in the STI group, but the proportion of CD26(high)CD4+ T-cells among CD4+ cells was significantly higher. Collectively, the 2 therapeutic agents induce a distinct immunologic status in CML patients whose hematopoiesis has returned to normal levels.