Characterization of a myeloperoxidase mRNA(+) acute lymphoblastic leukemia cell line (EU-1/ALL) established from a child with an apparent case of ALL.

A myeloid-antigen-positive acute lymphoblastic leukemia (My+ALL) cell line (EU-1) was established from the bone marrow cells of a child with apparent ALL. By morphology, cytochemistry and fluorescent-antibody phenotyping, EU-1 cells appeared to be lymphoblastic (L1 morphology, TdT+, CD10+, CD19+). However, by a sensitive immunocytochemical assay, EU-1 cells additionally displayed several myeloid antigens (CD13, CD14, CD33) not detected by flow-cytometry. Furthermore, EU-1 cells were cytochemically and immunocytochemically negative for myeloperoxidase (MPO) but positive for MPO mRNA by Northern blot analysis. After incubation with dimethylsulfoxide (DMSO), myeloid cell surface antigens were detected on EU-1 cells by flow cytometry, and a marked decrease in MPO mRNA expression was observed. These results demonstrate that EU-1 is a unique ALL cell line representing a significant subset of pediatric ALL patients who also express myeloid antigens and have poor prognosis.