Colocalization of FcRn and bacteria in PMNs. (A) Paraformaldehyde-fixed and saponin-treated PMNs after phagocytosis of Alexa488-labeled IgG-opsonized pneumococci (green) were analyzed through middle sections of cells by confocal microscopy. FcRn was visualized with a rabbit anti-FcRn antiserum (red). Bacteria, FcRn staining, and overlay are shown from left to right, respectively. (B) Fluorescence intensity (FI) of corresponding color channels shown in panel A were analyzed for whole cells showing enhanced localization of FcRn around phagosomes. In the rightmost panel, FI of FcR (red) and pneumococcal (green) are overlaid. (C) FI of pneumococci (green) and FcRn (red) across the cell along the line indicated (A, right; scale in arbitrary units). Experiments were repeated 3 times, yielding similar results.