3 µg of Anti-CD8a-APC or anti-CD8a-PE (clone: 53-6.7 from eBioscience) or purified rabbit anti-mouse collagen IV (Novus Biologicals) were injected intravenously (i.v.). Three minutes later, the animals were sacrificed, lavaged to remove cells in the airway, bled, and perfused with 10 ml of cold PBS. The spleen, LNs, lung, liver, and small intestine were harvested within 12min, and lymphocytes were isolated as described (19 (link)). Immunofluorescence staining was performed as described (6 (link)).