Preclinical studies of a panel of 12 monoclonal antibodies in view of bone marrow purging in acute lymphoblastic leukemia.

We analysed the optimal conditions for autologous bone marrow purging using complement binding monoclonal antibodies (mAbs). Twelve mAbs belonging to four clusters (CD9, CD10, CD19, CD24), alone or combined were evaluated by using direct cytotoxicity and clonogenic assays. We observed the following data: (1) optimal cytotoxicity was reached with doses of 1-10 micrograms mAbs for 10(7) cells, (2) the concentration of the cell suspension had to be below 3 X 10(7)/ml, (3) combinations of mAbs were more effective than a single mAb treatment, (4) in the case of an IgM isotype, there seems to be a clear dissociation between the amount needed for optimal toxicity and that for antigenic saturation measured by cytofluorometry.