1. Cell doping: Cryopreserved samples of patient CLL cells will be added to either RPMI culture medium or normal human blood (in three concentrations). B-cells isolated as described in A above will be incubated with the appropriate Peptide-dye conjugate for 30mins at 37OC. Cells will be washed and analyzed for peptide binding by flow cytometry. Similarly, A20 cells will be added to normal mouse blood and tested with A20 specific peptide-dye conjugates.