Characterization of CD44 isoforms on CLL and non-CLL B cells. (A) Lysates from 2 × 107 B-CLL cells that had been in RPMI/0.1% FCS for 24 hours were immunoprecipitated with the indicated Abs (control: anti-HLA) and analyzed by Western blotting. (B) The membrane fraction from the same B-CLL samples shown in panel A and from the indicated B cells was analyzed by Western blotting using anti-CD44 Abs. The presence of the 190-kDa CD44v isoform on B-CLL cells is indicated. A vertical line has been inserted to indicate a composition of 2 different gels. (C) The cell lysate from a representative B-CLL sample was immunoprecipitated with anti–MMP-9 Abs and analyzed by Western blotting using Abs specific for CD44 variable exons. Lysates from BLM cells were used as control for the anti-v6 mAb. (D) B-CLL cells were incubated with or without proMMP-9 in the presence or absence of the indicated Abs, and binding was analyzed by flow cytometry. Average values are shown. Const MMP-9 indicates constitutive MMP-9. *P ≤ .05.
