Relation of some cytochemical activities to the expression of CD34 marker in acute leukemia

The blast cells of peripheral blood and bone marrow of eleven acute leukemia patients with CD34 surface membrane antigen expression were investigated by immunophenotyping, cytochemistry and biochemical analysis. CD34 expression is a characteristic marker of very immature leukemic cells. Nine of eleven CD34+ acute leukemia cases had the immunophenotype of poorly differentiated myeloid cells. CD34+ blasts of two patients expressed the phenotype of very early lymphoid differentiation. Significant correlation was found between the expression of HLA-DR and CD34. The absence of CD10 antigen expression was observed in all cases of CD34+ myeloid blasts. The strong activity of SBB along with simultaneous absence of light microscopy MPO staining, 5'NT and moderate BG reactivity were characteristic enzyme features of CD34+ myeloid cells. The enzyme features of more mature stages of myeloid differentiation lacked. In lymphocytes, the CD34 expression correlated with CD10 antigen positivity and 5'NT activity. The activity of ADA was higher than that of PNP in all cases of CD34+ acute leukemia blast cells. The SBB, 5'NT and BG reactivity in correlation to CD34 antigen expression in acute leukemia may be an additional marker of very early stages of differentiation, either lymphoid or myeloid. The contribution to clinically important differential diagnosis of immature acute leukemia is discussed.