Aberrant co-expression of CD19 and CD56 as surrogate markers of acute myeloid leukemias with t(8;21) in Taiwan.

Aberrant antigen expression in acute myeloid leukemia (AML) has been extensively studied in the West with limited reports from Taiwan. We carried out this retrospective study to characterize the frequency and significance of aberrant antigen expression of AML in Taiwan. Among 111 cases, 58 (52%) showed aberrant antigen expression, most frequently CD7 (27%) and CD56 (23%). Aberrant CD7 expression was observed in all non-AML-M3 subtypes, most frequently in AML-M7 (4/6, 67%); while CD19 expression was only observed in AML-M2 (5/36, 14%). CD56 expression was most common in AML-M5 (4/8, 50%). The relative frequency of CD19 and CD56 expression in AML with t(8;21) was higher than those with other chromosomal abnormalities or normal karyotype (P = 0.011 and 0.005, respectively). In non-M3 AML, aberrant antigen expression was identified in 56/96 (58%) cases, in contrast to 2/15 (13%) AML-M3 cases (P = 0.001). CD7, CD19 and CD56 expression was not correlated with remission rate. We concluded that aberrant immunophenotype was more frequent in non-M3 leukemias in Taiwan. The relative frequency of CD19 and/or CD56 expression in AML with t(8;21) was significantly higher than those without this translocation and co-expression of these two antigens may serve as the surrogate markers for AML with t(8;21).