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 le ukemia patients with CD34 surface membrane antigen expression were inv estigated 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 immunopheno type of poorly differentiated myeloid cells. CD34+ blasts of two patie nts expressed the phenotype of very early lymphoid differentiation. Si gnificant correlation was found between the expression of HLA-DR and C D34. The absence of CD10 antigen expression was observed in all cases of CD34 + myeloid blasts. The strong activity of SBB along with simult aneous 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 anti gen 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 a cute leukemia may be an additional marker of very early stages of diff erentiation, either lymphoid or myeloid. The contribution to clinicall y important differential diagnosis of immature acute leukemia is discu ssed.