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 myeloblastic leukemia (AML) was analyzed using a wide panel of monoclonal antibodies (mAbs). Leukemic blasts were tested by applying direct immunofluorescence analysis and dual-fluorescence staining, and two groups of patients were identified: 56/110 (51%) expressing only myeloid antigens (My/AML) and 54/110 (49%) expressing both myeloid and lymphoid antigens (Ly/AML), CD13 and CD33 were expressed in almost all FAB subtypes, whereas CD14, frequently expressed in M4 and M5 subtypes (70%), was rarely expressed in M0 + M1 cases (9%). On the contrary, CD34, expressed in 77% of M0 + M1 cases, was practically absent in M3 and M5 subtypes (6% and 7%, respectively). CD2 and CD7 antigens were found in 34% and 42% of patients respectively, whereas B cell-associated antigens, such as CD10 and CD19, were found in 31% and 18% of patients. Cytogenetic abnormalities characteristically present in AML patients were also analyzed and, except for t(8;21) which was found in both groups of patients, the other abnormalities were frequently found in cases coexpressing lymphoid-associated antigens. Finally, the complete remission (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 with CD34^- patients (65% versus 82%) (p = 0.05) which became more evident when the mean intensity of fluorescence was considered. In conclusion, mAbs conjugated with fluorochromes and analyzed by more sophisticated cytometers allow the identification of a higher number of AML cases bearing lymphoid- associated antigens, but this phenotypic coexpression is not associated with biologically distinct forms of leukemia.