Susceptibility to Infection Due to Diminished Interferon-α-Producing Capacity in Patients with Refractory Anemia with Excess of Blasts or Refractory Anemia with Excess of Blasts in Transformation.

Peripheral whole blood cells from normal subjects and from 8 patients with refractory anemia with excess of blasts (RAEB) and one patient with RAEB in transformation (RAEB-t) were studied to ascertain their interferon (IFN)-α-producing capacity. This capacity was determined by time-resolved immuno-fluoroassay 20 hrs after the blood cells had been incubated with 500 HA/ml of Sendai virus. The mean IFN-α-producing capacity in the peripheral whole blood cells of 35 normal males was 8718 ± 4683 IU/ml, while that of 49 normal females was 7549 ± 4731 IU/ml; not a significant difference. All of the RAEB and RAEB-t patients examined showed a significantly low (<2500 IU/ml) IFN-α-producing capacity in the peripheral whole blood cells. In addition, the levels of IFN-α-producing capacity in 1 ml cell suspension containing 1 x 10(6) peripheral mononuclear blood cells were markedly lower in all 5 RAEB patients and the RAEB-t patient examined than those in the normal subjects, when 5 HA of Sendai virus was used. The activities of natural killers were lower in the RAEB/RAEB-t patients than those in the normal subjects. These findings suggest that IFN-α-producing capacity is diminished in the peripheral whole blood cells of RAEB and RAEB-t patients, and great care is advised regarding infection by virus and bacteria in treatment of these patients.