Myeloid cell surface phenotype in myelodysplasia: evidence for abnormal persistence of an early myeloid differentiation antigen.

A panel of monoclonal antibodies recognizing myeloid cell surface differentiation-associated antigens was used to study the peripheral blood myeloid population of 23 patients with myelodysplastic syndromes (MDS) and 23 controls. A marker for immaturity, defined by the presence of the antigen recognized by the My9 antibody, was found to persist on the surface of mature neutrophils in a subgroup of MDS patients. Abnormal My9 positivity was concentrated primarily, but not exclusively, in previously described morphologically defined subgroups of MDS patients considered to be at highest risk for leukemic conversion. Longitudinal study of a larger number of patients will be required to test the hypothesis that abnormal persistence of My9 may have prognostic significance.