Fig. 3. Peptide-MHCII complexes derived from cytosolic proteins are formed in lysosomal compartments in different APCs. (A,B) BMC-2 cells transfected as in Fig. 2A with E_52-68-eGFP (A) or eGFP (B) were fixed 12 hours after transfection, permeabilized and stained with Y-Ae and anti-LAMP-1 antibodies. (C,D) C57Bl/6 macrophages were pulsed cytosolically (C) or exogenously via the fluid phase (D) with GST E_52-68-myc protein (5 mg/ml), chased for 15 minutes, fixed, permeabilized and stained with YAe and anti-LAMP-1 antibodies. Images are single representative confocal sections. All images on the very right are respective overlays of the stained images of A, B, C and D. Scale bar, 10 µm.