OBJECTIVETo investigate the expression of CD123 and its significance in lymphocytic leukemia.

METHODSCD123 expression in 139 lymphocytic leukemia patients and in lymphocytes from 10 normal bone marrows (BM) was analyzed by multi-parameter flow cytometry. Cytogenetic and minimal residual disease (MRD) analysis were performed in acute B-lymphocytic leukemia (B-ALL) patients.

RESULTSCD123 expression was absent in B lymphoid lineage stem-progenitor cells, mature B and T lymphocytes from 10 normal BM. Among 139 lymphocytic leukemia patients, CD123 was negative in 5 T-ALL and 23 B-CLL patients. However, among 111 B-ALL patients, CD123 was expressed in 106 (12 pro B-ALL, 57 common B-ALL and 37 Pre B-ALL) (95.49%) but not in 5 mature B-ALL patients. There was a positive correlation between CD123 and p-Akt expression, and CD123 expression was much higher in hyperdiploid than in non-hyperdiploid B-ALL patients. A statistically significant difference in relapse rate within 12 months (MRD positive group: 63.04% vs MRD negative group 21.56%)and in disease free survival (DFS) time was found beween patients with MRD\[(36.06 +/- 2.62)%\] or not \[(48.23 +/- 1.82)%\] (P < 0.01). Moreover, stable CD123 expression could be observed in B-ALL patients in relapse.

CONCLUSIONSCD123 was predominantly expressed in B-ALL patients and remained in patients in relapsec, indicating that it may be an useful MRD marker in B-ALL patients.