Acute lymphoblastic leukemia of NK-cell lineage: responses to IL-2.

Acute lymphoblastic leukemias with phenotypic characteristics of natural killer cell derived lineage are extremely uncommon. We identified an ALL with a phenotype consistent with an NK-cell of origin. The blasts underwent a proliferative response to r-IL2 in culture but showed no spontaneous or r-IL2 or gamma-INF induced cytotoxicity. With r-IL2 stimulation however, the tumor cells demonstrated a dramatic acquisition of low density CD8 surface positivity and a loss of CD11b expression after short term culture. By comparison to ALL of B or T lineage, NK ALL likely represents an early stage of bone marrow derived NK-cell precursor.