ANALYSIS OF MYELOID CHARACTERISTICS IN ACUTE LYMPHOBLASTIC-LEUKEMIA

We examined myeloid characteristics of myeloid-antigen-positive (My+) and -negative (My-) B-precursor acute lymphoblastic leukemia (ALL) blast cells. Immunophenotyping before and after culture, rearrangements of immunoglobulin heavy chain (IgH) and T-cell receptor (TCR) genes, stimulation of DNA synthesis with granulocyte colony-stimulating factor (G-CSF), and G-CSF binding assay were performed. Of My+ ALL blasts, the immunophenotypic staging as B-precursor ALL and rearrangements of IgH and TCR-beta, gamma and delta genes did not differ from findings in My- ALL blasts. Stimulated with G-CSF, cells from one My+ ALL and from one My- ALL patients showed enhancement of DNA synthesis and expression of CD11b and CD13, respectively. G-CSF binding was observed in blasts from 3 Mv+ ALL patients and one My- ALL child. After culture, blasts from My- ALL children expressed CD13 but showed neither enhanced DNA synthesis with G-CSF nor G-CSF binding. Thus, it would appear that (i) My+ and My- adult ALL blasts are at the same stage of differentiation; (ii) some My+ adult ALL blasts have phenotypic and functional myeloid characteristics; and (iii) induction of CD13 expression in Mv- ALL after in vitro culture does not correlate with other myeloid characteristics.