[Biphenotypic leukemia in childhood--analysis of 19 cases]

The leukemic cells of 19 patients (pts) out of 180 children with acute leukemia expressed both CD 19 (B 4) and CD 13 (MY 7) antigens. These biphenotypic leukemias (BiL) were divided into 3 groups on the basis of clinical features, antigen profiles and karyotypes. GroupI pts (N = 6) were infants under one year of age with high initial white blood cell (WBC) count over 200,000/microliters. The blasts of this group did not express CD 10 (J 5) antigen. In 4 of these pts, the blasts initially did not express CD 13 antigen, however, they became strongly positive after short-term culture without stimulation. Cytogenetic analysis revealed a breakpoint at 11 q 23. Group 11 pts (N = 6) were often school age and had a high WBC count over 100,000/microliters and CD 10 positive blasts. The blasts of 4 pts did not express CD 13 antigen until short-term culture. Cytogenetic marker was Ph1 chromosome. Group III pts (N = 7) were often preschool age and the WBC count was lower than that of other groups. The blasts expressed CD 10 antigen with normal karyotypes or various karyotype abnormalities. Prognosis of pts with BiL was more poor than that of CD 13- common ALL, and among 3 groups survival of Group I and II was significantly shorter than that of group III. This study suggests that childhood BiL represents heterogeneous leukemias. It is important to distinguish BiL in childhood acute leukemia and further divide into the groups in order to establish an adequate therapy for prognostically poor BiL.