FIGURE 5.

(A,B) Co-culture of tumour cells with stromal cells significantly decreases surface levels of the CD20 molecule. Raji (A) and Daudi (B) cells were cultured for 24 h on either plastic (black bars) or M2-10B4 (gray bars) or HS-5 (checked bars). After 24 h, cells were collected and either left unlabelled, or incubated with isotype control (mouse IgG2b-APC), or anti-CD20-APC antibody (0.24 μg/mL). Percentage of positivity to the antibodies was measured as % of PKH67- cells which were APC+. The MFI (geometric mean fluorescence intensity) measured for isotype controls was then subtracted by the MFI of stained samples. Data is mean ± SEM of three independent experiments performed in duplicate.