A Ph1 chromosome positive B cell line expresses the fusion protein P 210.

We established a B lymphocyte line from bone marrow cultures of a patient with Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia. The cell line (MB) is positive for Ph1 and has the phenotype of mature B lymphocytes transformed by the Epstein-Barr virus (EBV). When DNA was isolated and hybridized to specific cDNA probes, a rearranged immunoglobulin gene and EBV-sequences were detected. On Western blots of cell extracts, the novel fusion protein (P 210) was demonstrated with antisera against bcr and v-abl proteins. These results confirm the concept that B lymphocytes in CML can be involved in the malignant clone and demonstrate that these B cells express the fusion protein.