Defect of NK activity in children with untreated acute lymphocytic leukemia (ALL). I, Dependence on the blast count and phenotype, and response to exogenous and endogenous alpha-interferon

Endogenous NK-activity (eNK) against K-562 cells was determined in peripheral blood of 68 children with acute lymphocytic leukemia (ALL) before treatment. In 53% of them it was depressed, and in 47% it was within the range of control children (27) and adults (104). Impaired eNK-activity has been attributed, in part, to dilution of NK cells by the blasts. Defects in production of IFN, and in response to it, may be additional reasons for depressed NK-activity in about 50% of children with untreated ALL