CLL cells express CD100 on the surface.

The leukemic cells from CLL patients were stained with PE–labeled anti-CD100 mAb and analyzed by flow cytometry. The analysis was performed gating on CD19⁺CD5⁺cells and the level of CD100 expression was measured by MFI. Dark histogram represents the fluorescence obtained with negative control isotype–matched mAb; white histogram shows positive cells in a representative case.