Fig. 2.

Pre-incubation with HER2+EpCAM+ TEX prevents binding of trastuzumab and C215 to HER2+EpCAM+ cancer cells. a trastuzumab and b C215 were titrated on BT474 cells to identify the antibody concentration that gives half-maximal staining. Trastuzumab c and e or C215 d and f at concentrations of 50 ng/ml were pre-incubated with 100 μg/ml HER2+EpCAM+ BT474 exosomes (c and d) or with the same amount of HER2−EpCAM− Mel624.38 exosomes (e and f). As a positive control, cells were stained with antibodies that were not pre-incubated with TEX. It became clear that pre-incubation with BT474 exosomes but not with Mel624.38 exosomes prevented trastuzumab and C215 from binding to BT474 cells. Grey histogram unstained cells. Bold line Maximal staining of trastuzumab and C215 on BT474 cells. Thin line staining of BT474 cells with pre-incubated trastuzumab. One out of the seven independent experiments is shown