Cell-surface gal-3 binds to CD45 on DLBCL cells. (A) To identify glycoprotein receptors for gal-3, endogenous gal-3 was immunoprecipitated from SUDHL-6 (S-6) and SUDHL-9 (S-9) cells that were biotinylated to label cell-surface glycoproteins. Precipitates were separated by SDS-PAGE and blotted to nitrocellulose and biotinylated gal-3–binding proteins detected with streptavidin-HRP. As expected, no gal-3–associated proteins were precipitated from SUDHL-9 cells. In SUDHL-6 cells, a single major gal-3–binding protein was detected at ∼ 250 kDa. (B) Immunoblotting with anti-CD45 of material immunoprecipitated in panel A confirmed that gal-3 precipitated CD45 from SUDHL-6 cells. (C) GCS-100 reduced the amount of CD45 associated with gal-3. SUDHL-6 cells were treated with GCS-100 or buffer control for 1 hour, endogenous gal-3 immunoprecipitated, and the amount of associated CD45 determined by immunoblot. WCL indicates whole-cell lysate; and IP, immunoprecipitate.