Figure 5

Neuronal Fc receptors play a role in antigen restriction. (A) Naïve mice were injected intraperitoneally with rabbit polyclonal anti-OVA antibodies, and 24 h later OVA-800CW or KLH-800CW was injected in the dorsum of the hind paw. The amount of OVA antigen was significantly decreased compared with KLH in the sciatic lymph nodes (mean ± SEM: KLH, 32.95 ± 7.741, n = 10 versus OVA, 6.483 ± 1.461, n = 9). (B) Antigen trafficking is not different in naïve FcR KO mice. Naïve Balb/c and FcR KO mice were injected subcutaneously in the hind paw with KLH-800CW. No difference was seen in the antigen signals of naïve Balb/c and FcR KO mice in the sciatic lymph nodes (mean ± SEM: Balb/c, 62.50 ± 5.614, n = 8 versus FCR KO, 71.48 ± 8.197, n = 6). (C) Increased antigen levels were observed in immunized FcR KO mice challenged with KLH-800CW (mean ± SEM Balb/c, 15.76 ± 2.721, n = 10 versus FCR KO, 44.29 ± 6.500, n = 11, p < .001 by t test). (D) Colocalization of antigen and Fc receptors on PGP9.5 + ve neuronal tissue at the site of injection. Mice immunized with KLH were challenged with KLH-A647 in the dorsum of the hind paw. After 1 h, skin around the injection site was excised, frozen in optimal cutting temperature media and sectioned at 10 µm. Tissue slices were mounted on slides, then stained with antibodies against PGP9.5 and FcγRI. Images were obtained on a laser-scanning confocal microscope. Images shown are representative of slices from three different animals. Blue indicates PGP9.5, green indicates FcγRI, red indicates signal from KLH-A647 and white in the merged image indicates colocalization of all three signals. Orange circles indicate regions of interest.