Immunomagnetic removal of L1210V leukemic cells from mouse bone marrow ex vivo.

The purging of mouse bone marrow from L1210V leukemic cells was attained ex vivo by using monoclonal IgM antibody against leukemic cells and magnetic particles charged with goat anti-mouse IgM antibodies (immunobeads), followed by magnetic separation. The monoclonal antibody MoAb-16 recognizes oncofetal antigen on target cells and binds to 100% L1210V cells. The number of the remaining clonogenic leukemic cells was examined by LCFU and bioassay tests. The clonogenic capacity of the bone marrow progenitor cells was measured by NCFU test. After first treatment cycle the number of LCFU was reduced in a dose-dependent manner. After second cycle of purification a complete elimination of L1210V cells from marrow was achieved at the concentration 10 mg/ml of magnetic particles. Although at lower concentrations of immunobeads no leukemic spleen colonies were found, some residual L1210V cells were still present in the bone marrow and were able to grow and kill the recipient mice. The loss of bone marrow progenitor cells during magnetic removal procedure was about 10%.