Figure 1.

Analysis of FcγR-mediated phagocytosis by phase contrast and confocal microscopy. FcγR-transfected COS cells were incubated with FITC-labeled sheep RBCs opsonized with IgG at 37°C for 1 h to allow internalization to occur. The cells were then subjected to a brief hypotonic lysis to remove externally bound RBCs and were fixed and stained to mark the COS plasma membrane. A and B illustrate a single FcγRIIA-expressing cell stained orange with ethidium bromide examined by both phase contrast and fluorescence microscopy that has internalized several RBC targets (arrows) into large vesicles. In C and D, confocal sections in two axes of the same cells show green RBC targets that appear within the COS membrane labeled with a WGA–rhodamine conjugate appearing red. C shows several sections in the z-axis, whereas D shows the y-axis of the same cell. The third axis, x, is similar to D and is not shown. Bar, 10 μm.