Unique Monoclonal Antibodies Against Soluble Membrane Proteins of Human CML Myelocytes Reactive with Human Myeloid Progenitor Cells

Monoclonal antibodies of IgGl type immunoglobulin, directed against soluble CML antigen isolated from the reactive CML peripheral myelocytes, were reported. These MAbs were further investigated for their reactivity by ¹²⁵I-protein-A binding assays, indirect immunoflorescence tests, cytotoxicity, SDS-PAGE, immunoelectrophoresis, and by immunodiffusion suggesting that they recognized antigens specific mostly to undifferentiated cells. These were tested against various leukemic peripheral blood leukocytes, bone marrow cells, established cell lines of various origin, and with many solid tumor cells and demonstrated specific reactivity with CML myelocytes alone and cell lines of myeloid origin. Indirect immunoperoxidase staining of single cell preparation revealed peroxidase localization in most promyelocytes and in few mature myelocytes from CML PBL/BM cells, thus helping in identifying the exact type (morphology) involved in reacting specifically with these Mabs.