Expression of myeloid differentiation antigens on myeloblasts in bone marrow of patients with myelodysplastic syndromes.

Bone marrow myeloblasts in 15 patients with myelodysplastic syndromes were quantitated with monoclonal antibodies using the immunoalkaline phosphatase technique. Positive blasts were identified in 7 of the 15 cases with at least one of three antibodies reactive with acute myelomonocytic leukaemic cells (PMN-6, PMN-29, AML 2-23) which were non-reactive with normal myeloblasts. In 5 of these cases increased PM-81 positivity was associated with expression of at least one of the other antigens (PM-81 antibody reacts with all types of acute myeloid leukaemic cells and a certain percentage of normal myeloblasts). The data suggest an aberration of myeloid differentiation in myelodysplastic syndromes which is reflected in altered surface marker features.