Upregulation of CD6 expression on B-CLL cells by activation with SAC plus IL-2 and TPA. B-CLL cells from L-156, L-38, and L-194 patients were cultured with or without SAC (0.005%) plus IL-2 (100 U/mL) or TPA (50 nmol/L) for 72 hours and analyzed for CD6 expression with IOR-T1 MoAb by flow cytometry. The dashed line represents background fluorescence and the solid line represents CD6 fluorescence. CD6-specific MFI is in the upper right corner of each panel. The x-axis corresponds to logarithmic fluorescence intensity and the y-axis to cell number.