INCIDENCE AND PROGNOSTIC RELEVANCE OF CD34 EXPRESSION IN ACUTE MYELOBLASTIC-LEUKEMIA - ANALYSIS OF 141 CASES

In 141 adult patients with diagnosis of acute myeloid leukemia the ove rall expression and intensity of expression of CD34 antigen on leukemi c cells was investigated. Myeloid blasts were tested by applying direc t immunofluorescence staining using anti-CD34 fluorescein monoclonal a ntibody in flow cytometry. CD34 antigen was found in 73 out of 141 (51 %) cases and in particular in M0, M1 and M4 French-American-British (F AB) cytotypes, while M3 and M5 cases were rarely positive. In patients whose blasts expressed CD34 antigen a significantly lower rate of com plete remission (CR) was observed as opposed to CD34 negative cases (6 1% vs 88%) (P = 0.001). Furthermore, a negative correlation between hi gh intensity of CD34 expression, measured as a mean fluorescence index (MFI), and CR rate was observed. In particular, patients with a highe r CD34 fluorescence intensity (MFI > 23), showed a further reduction i n CR rate (48%). Also, these patients had a significantly lower overal l survival (P = 0.03) as compared to patients with no expression of CD 34 and patients with CD34 MFI < 23. In conclusion, these findings conf irm that CD34 expression is frequently associated with ''immature'' FA B cytotypes (M0, M1 and M4) and with a reduced probability to achieve CR. Furthermore, a high CD34 intensity of expression should be conside red as a reliable poor prognostic factor. (C) 1997 Elsevier Science Lt d.