THE PRESENCE OF LYMPHOID-ASSOCIATED ANTIGENS IN ADULT ACUTE MYELOID-LEUKEMIA IS DEVOID OF PROGNOSTIC RELEVANCE

The immunophenotype of 110 adult patients with diagnosis of acute myel oblastic leukemia (AML) was analyzed using a wide panel of monoclonal antibodies (mAbs). Leukemic blasts were tested by applying direct immu nofluorescence analysis and dual-fluorescence staining, and two groups of patients were identified: 56/110 (51%) expressing only myeloid ant igens (My/AML) and 54/110 (49 %) expressing bath myeloid and lymphoid antigens (Ly/AML). CD13 and CD33 were expressed in almost all FAB subt ypes, whereas CD14, frequently expressed in M4 and M5 subtypes (70%), was rarely expressed in M0 + M1 cases (9%). On the contrary, CD34, exp ressed in 77% of M0 + M1 cases, was practically absent in M3 and M5 su btypes (6% and 7%, respectively). CD2 and CD7 antigens were found in 3 4 % and 42% of patients respectively, whereas B cell-associated antige ns, such as CD10 and CD19, were found in 31% and 18% of patients. Cyto genetic abnormalities characteristically present in AML patients were also analyzed and, except for t(8;21) which was found in both groups o f patients, the other abnormalities were frequently found in cases coe xpressing lymphoid-associated antigens. Finally, the complete remissio n (CR) rate, survival and event-free survival were analyzed according to the presence of lymphoid markers and also of some specific antigens such as CD7 and CD34. The only prognostic difference was represented by CD34(+) patients who showed a reduction in the CR rate compared wit h CD34(-) patients (65% versus 82%) (p = 0.05) which became more evide nt when the mean intensity of fluorescence was considered. In conclusi on, mAbs conjugated with fluorochromes and analyzed by more sophistica ted cytometers allow the identification of a higher number of AML case s bearing lymphoid-associated antigens, but this phenotypic coexpressi on is not associated with biologically distinct forms of leukemia.