Childhood acute lymphoblastic leukemia with natural killer activity. Clinical and cellular features of three cases

Leukemic cells from 3 of 28 children with acute lymphoblastic leukemia (ALL) had natural killer (NK) activity against K562 and Molt-3, but not against Raji as determined by the 4-hour 51Cr release assay at a 40:1 effector:target ratio; the highest percent lysis against K562 in each patient ranged from 55.9% to 147.4% of the normal lymphocyte value and that against Molt-3 from 28.0% to 127.9%. Their leukemic cells were nonphagocytic, nonadherent, and negative for nonspecific esterase. Leukemic cells from two of them displayed similar morphologic and immunologic features. The cells had a round nucleus, and were E-receptors (E)+, Leu-5+, IgG-Fc+, Ia+, OKM1+ or OKM1-, T-cell antigens-, B markers-, and monocyte antigen-, indicating their NK cell origin. The other patient's cells were characterized by the irregularly shaped nucleus, and were E+, Leu-5+, IgG-Fc+, T+, OKT6+, Leu-2a+, and OKM1+. The presence of E which are identical to E of T-cells and a high density of T-cell antigens including OKT6 on the cells suggested their T-cell nature. Of the three patients, two without thymic enlargement had leukemic cells of NK cell origin, and the other one with the symptom leukemic cells of the T-cell lineage, the clinical feature probably reflecting the cell lineage of their leukemic cells.