Antibody feeding of IFITM expressing cells.

<p>Live A549-IFITM-HA cells were incubated with 5 µg/ml anti-HA at 37°C to allow endocytosis of bound antibody molecules. Subsequently, the cells were washed, fixed, permeabilised and incubated with an anti-rat Alexa-488 conjugate. A) Control A549 cells show no specific staining. B) In IFITM1-HA cells the majority of labelling is at the plasma membrane. C) IFITM3-HA cells that were not incubated with anti-HA antibody show no labelling. For IFITM2-HA and IFITM3-HA expressing cells (D and E) the majority of cells are not labelled, however in both cases a minority of cells do show punctate labelling indicative of IFITM-mediated internalisation of anti-HA antibodies. In D and E, the boxed region has been enlarged. All images were taken using the same microscope settings and adjusted uniformly. Scale bars represent 15 µm.