CTCL cells express a functional ILT2/CD85j receptor.

(A) Probing of the CTCL-derived cell lines Pno and Cou-L for presence of SHP-1: Western blot of whole cell lysates with an anti–SHP-1 polyclonal antibody. T-cell-rich PHA–stimulated PBLs served as positive controls. (B) ILT2/CD85j recruits SHP-1 in Pno cells: ILT2 immunoprecipitates from pervanadate-untreated and pervanadate-treated Pno cells were blotted with an anti–SHP-1 antibody. (C) Cross-linking of surface ILT2 inhibits the anti-CD3–induced proliferation while not affecting the cytokine-driven proliferation of Pno cells. Pno cells (3 × 10⁴) were activated with immobilized anti-CD3 mAb or IL-7 as described in “Patients, materials, and methods,” in the presence of medium alone (white histograms), in the presence of isotype control mAb (gray histograms), or in the presence of anti-ILT2 mAb (black histograms), cross-linked with GAM Ig.