Overexpression of CD123 correlates with the hyperdiploid genotype in acute lymphoblastic leukemia.

We evaluated CD123 expression in 95 pediatric and 24 adult ALL patients and compared the results with the CD123 expression in normal B-cell precursors. Early B-cell precursors were negative while intermediate precursors and mature B cells showed weak CD123 expression. Leukemic blasts in 31% of precursor-B ALL samples exhibited strong expression of CD123, 61% had moderate CD123 expression and 8% were negative; 81.5% of ALL with hyperdiploid karyotype (>/= 52 chromosomes) showed strong CD123 overexpression. In contrast, cases with ETV6/RUNX1 rearrangement had weak CD123 expression. Our study suggests that overexpression of CD123 is an aberrant phenotype present in a subset of precursor-B ALL with hyperdiploid genotype, and represents an additional marker of good prognosis in pediatric precursor-B ALL. Moreover, aberrant CD123 expression in ALL is a good marker for monitoring of minimal residual disease.