ATMs in visceral fat are efficient phagocytes capable of processing model antigens. A: Identification of fluorescent OVA (green) in F4/80+ (red) ATMs in eWAT by confocal microscopy 1 h after intraperitoneal injection of FITC-conjugated OVA. Bar = 50 μm; original
magnification ×40. B: Immunofluorescence image of fluorescent OVA (red) in a FALC in eWAT from a lean mouse. Scale bar = 100 μm. SVCs were isolated
from HFD-fed (20 weeks) male mice and cultured for 18 h. Adherent cells were incubated with FITC-conjugated OVA or FITC-labeled
ZymosanA particles for 1 h before immunostaining with indicated antibodies and imaged by confocal microscopy (original magnification
×63). Ex vivo uptake of FITC-OVA (green) was observed in adherent F4/80+ (red) (C), MHC I-A/I-E+ (red) (D), and CD11c+ (red) cells (E). F: Phagocytosis of ZymosanA particles (green) by cultured F4/80+ ATMs (red). Scale bar = 50 μm for C–F. Lean mice were injected intraperitoneally with DQ-OVA (100 μg/mouse). SVCs from eWAT and peritoneal macrophages were isolated
1 h later and stained for flow cytometry analysis. Representative scatterplots show DQ-OVAHigh cells in ATMs expressing MHC I-A/I-E (F4/80+ CD11b+) (G) and non-ATMs (F4/80− CD11b−) (H) from eWAT. I: DQ-OVA signals were detected in peritoneal macrophages (PMϕ; F4/80+ CD11bHigh) from the same mouse; the percentage of gated cells is indicated in each quadrant.