Aberrant expression of KOR-SA3544 antigen in childhood acute lymphoblastic leukemia predicts TEL-AML1 negativity

The antigen KOR-SA3544 is physiologically expressed exclusively on granulocytes. Aberrant expression of KOR-SA3544 has been invariably found in BCR/ABL-positive acute lymphoblastic leukemia (ALL) and in some BCR/ABL-negative ALL. In an interim analysis of a prospective clinical and cytometric study data of 73 children with newly diagnosed or relapsed ALL with and without TEL/AML1 fusion are presented. KOR-SA3544 expression over 3% was detected in the majority of TEL/AML1-negative patients with newly diagnosed common or preB ALL (19 of 31) and not in TEL/AML1-positive patients (0 of 18, P < 0.0001). the level of expression of kor-sa3544 was 0.02–90% (median 6.0%) and 0.03–2.4% (median 0.23%) in tel/aml1-negative and tel/aml1-positive patients, respectively. all five newly diagnosed patients with dna index ⩾1.16 and <1.6 exhibited high levels of kor-sa3544 expression. membrane expression of cd79a was found to correlate with tel/aml1 negativity, although less significantly than kor-sa3544 (P = 0.03). Furthermore, our data confirm that TEL/AML1 positivity correlates with non-hyperdiploidy and low presenting age. In conclusion, KOR-SA3544 correlated strongly with TEL/AML1 negativity, it was a better predictor of TEL/AML1 status than other factors tested and was found at high levels in hyperdiploidy. In combination with age, KOR-SA3544 predicted TEL/AML1 status in 86% newly diagnosed preB/cALL patients.