[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.