The effect of recombinant alpha-interferon on natural killer cell activity and clinical course in patients with myelodysplastic syndrome.

Thirteen patients with myelodysplastic syndrome (MDS) were included in this study and consented to treatment with recombinant alpha-interferon (a-IFN). These patients were subclassified: six as RAEB, one as RAEB-T and six as CMML. T-cell subsets and natural killer cells were identified in the peripheral blood with the use of monoclonal antibodies and natural killer cell activity (NKa) was assayed before, during and after a-INF treatment. The treatment schedule consisted of 2.0 MU/m2 sc t.i.w. continuously for the three months. Prior to treatment, NKa was found decreased in 11 of 13 patients as compared to that of normal individuals. Following a-IFN administration, a rise of NKa was observed in eight of the eleven patients. In those who responded, a-IFN was continued for 1 to 21 months. Alpha-IFN treatment was myelosuppressive for most of the patients, but transient increase of the number of neutrophils and platelets was observed in 3 and of the reticulocytes in one patient. Disease progression was recorded in 9/13 patients (69%) at a median time of 17.3 months. The median overall survival was 30.5 months (range 7.5 to 65+ months). No evidence of a relationship was found between the rise in Nka and the limited clinical improvement observed. Two NKa responders under continuous a-IFN treatment are in stable clinical condition for 36+ and 65+ months. The study provides only limited evidence that a-IFN may improve the clinical course of patients with MDS.