Localization of FcRn within PMNs. FcRn expression in human granulocytes was analyzed by costaining with (A) myeloperoxidase (10-nm gold particles) or (B) lactoferrin (15-nm gold particles) using transmission electron microscopy. FcRn is visualized as 15-nm (A) or 10-nm (B) particles (white arrows). N indicates nucleus; PM, plasma membrane.