Activity of natural killers in acute leukemia in children

Natural killer (NK) activity was studied in healthy children, (16) and those with acute leukemia at different phases of the disease (63). Patients' age ranged 3-11 years. NK activity was measured by release of 51Cr from the labelled K 562 target cells. A sharp decrease in NK activity was found in the acute phase, irrespective of the morphologic pattern of acute leukemia, the degree of blastosis and therapy. 75% of patients achieving remission revealed a decreased NK activity within the first 24 months, while in 25% it was normal. At 3 years and later, the majority of responders showed normal NK activity.