Stimulated ILT3 and BCR cocluster in a confined membrane region where ILT3 inhibits BCR-dependent activation of Akt. (A) Representative immunofluorescence images of CLL cells, either resting or stimulated for 15 minutes as indicated. Staining represents surface ILT3 and BCR. (B) Quantitative analysis of surface BCR polarization toward the ILT3 pole in CLL cells stimulated for 15 minutes as indicated. Dots represents single cells. The analysis is representative of experiments with CLL cells from 5 donors. (C) Representative immunoblot of CLL cells stimulated with beads coated individually with isotype control, ILT3- and BCR-specific antibodies, or with their combination, as indicated. (D) Quantitative immunoblot analysis (n = 3 experiments). Scale bars represent 5 μm. Shown are mean values ± SD. **P < .01; ***P < .001. DIC, differential interference contrast image.