Usefulness of CD11a and CD18 in flow cytometric immunophenotypic analysis for diagnosis of acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is an aggressive disease that requires prompt diagnosis and therapy. Flow cytometry immunophenotyping can serve as a screening test for APL before the results of cytogenetic or molecular testing for t(15;17)(q22;q21)/PML-RAR a are available. CD11a and CD18 are leukocyte β2-integrin subunits expressed in most acute myeloid leukemia (AML) types, but are often dimly expressed or absent in APL. We used flow cytometry immunophenotyping with an antibody panel including CD11a and CD18 to assess 36 APL and 33 other AML cases. HLA-DR, CD11a, and CD18 were absent in 81% of APL and 12% of other AML cases (specificity, 88%). By further including combinations of HLA-DR-, CD2+, and either CD11a- or CD18-, we identified 92% of APL cases with 85% specificity. These data compare favorably with the combination of HLA-DR- , CD34-, and CD117+ for APL diagnosis, which had a sensitivity of 64% in this study.