Fig. 4. Intracellular sequestration of dextran in control and IFN treated T84 monolayers. (A) Control, (B) IFN -treated (10 ng/ml; 48 hours) and (C) Ca²⁺-depleted T84 monolayers were incubated with 1 mg/ml Rhodamine-labelled 10 kDa dextran for 60-120 minutes as described in Materials and Methods. After fixation, monolayers were stained with the nuclear stain DAPI and analysed by confocal microscopy (x-z) images. Reconstructed confocal images in the x-z plane showing staining for Rhodamine-dextran, DAPI and merged images of the two stains are shown for each of the three groups. Dextran internalisation increased following Ca²⁺ depletion (areas of intense staining indicated by arrows) whereas IFN-treated monolayers showed no change compared to untreated controls. `F' denotes the position of the Transwell filter, which exhibited high levels of dextran staining in all groups. Bar, 50 µm.