Figure 3.

Effect of proteins and antibodies on BSDL transcytosis. Int407 cells were grown on Transwell inserts to obtain a tight epithelium. BSDL (10 μg/ml or 100 nM) was independently incubated for 30 min (37°C under gentle agitation) in the culture medium with 10 μg/ml Grp94 or transferrin. Alternatively antibodies (10 μg/ml) were preincubated with cells for 30 min in the culture medium. Then cell culture medium of the apical reservoir was removed and replaced by fresh medium containing BSDL and Grp94 or transferrin, whereas BSDL (100 nM) was directly added into the apical compartment of cells preincubated with either antibodies. After 3-h incubation, the medium of the bottom reservoir was removed, and the amount of BSDL evaluated from its activity. Values are expressed as percent of control performed in the absence of companion protein or ligand (control) or in the presence of unrelated antibodies (control not shown). Values are means ± SD of at least three independent experiments.