Figure 6

Analysis of apoptosis after anti-CD44 ligation. (A) Apoptosis was analyzed after incubation of cells for 24 h with anti-CD44 mAb (20 μg/ml) or isotope control antibody (20 μg/ml) by annexin-V/PI staining and measured by flow cytometry as shown for cell lines EB-1 (CD44^-) and REC-1 (CD44⁺). Data are representative of three independent experiments with similar results. (B) Mean of early apoptotic cells (annexin-V⁺, PI^-) in two CD44⁺ (REC-1 and KM-H2) and two CD44^- (EB-1 and KARPAS-299) lymphoma cell lines after treatment with anti-CD44 in different concentrations for 24 h (n = 3). The number of early apoptotic cells in the corresponding isotope controls were set to 1. Note that anti-CD44 induced apoptosis occurred only in the CD44⁺ cell lines.