Immunocytochemical evaluation of abl-gene products in leukemic cell lines

We raised monoclonal antibody (MAb) against a synthetic oligopeptide corresponding to a portion of the predicted v-abl protein sequence (379-390). This MAb reacted with all of the abl-gene products (p145c-abl, p150c-abl and p210bcr-abl fused protein) and was not specific for any one of them. Immunocytochemically, we investigated the expression and localization of the abl-gene products in various leukemic cell lines. Positive immunoreactions were observed in Ph1 positive leukemic cell lines (K562 and KU-812) and erythro-leukemic cell lines (HEL and K3D) and were located on the cell membrane. Electron microscopically, a different distribution pattern was observed among the cell lines: linear and almost even in Ph1 positive leukemic cell lines, whereas spotted or budding-like in erythroleukemic cell lines. Ph1 translocation produces p210bcr-abl fused protein with not only altered autophosphorylation activities but also altered subcellular distribution patterns.