Heterologous epitopes of IRBP protect against autoimmune uveitis induced by the autologous epitope.
Peptide 161-180 of human interphotoreceptor retinoid-binding protein (IRBP) contains a major uveitogenic epitope for mice of the H-2r haplotype. The human and bovine homologs differ from the autologous murine homolog by three and four amino acid residues, respectively. We compare the immunogenicity and pathogenicity of the three homologs, and investigate their ability to induce oral tolerance to experimental autoimmune uveoretinitis (EAU) induced by the autologous peptide. All three 161-180 homologs were pathogenic, with a hierarchy: human > murine > bovine. All crossreacted with each other and with IRBP. Feeding any of the three homologs (6 x 200 microg over 2 weeks) lowered antigen-specific responses and protected from EAU induced by the autologous homolog, and reduced EAU induced with whole IRBP. Peptide-fed mice had a reduced frequency of peptide-reactive T cells, suggesting a mechanism involving anergy and/or deletion. The results indicate that non-identical, but crossreactive, heterologous epitopes can protect against EAU induced by the corresponding autologous epitope, and even by the whole multi-epitope protein. These findings may impact on clinical trials in which uveitis patients are undergoing oral immunotherapy with bovine retinal antigens.
Silver
P B
PB
Laboratory of Immunology, National Eye Institute, Bethesda, MD 20892, USA. pbs@box-p.nih.gov
Rizzo
L V
LV
Sun
B
B
Chan
C C
CC
Wiggert
B
B
Nussenblatt
R B
RB
Caspi
R R
RR
D000284:Administration, Oral; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D002417:Cattle; D003429:Cross Reactions / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D000939:Epitopes / Q000008:administration & dosage / Q000276:immunology*; D005136:Eye Proteins; D006801:Humans; D007958:Leukocyte Count; D051379:Mice; D008815:Mice, Inbred Strains; D010446:Peptide Fragments / Q000276:immunology; D012177:Retinol-Binding Proteins / Q000276:immunology*; D017385:Sequence Homology; D013601:T-Lymphocytes / Q000276:immunology / Q000473:pathology; D014605:Uveitis / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D000099214:Retinol-Binding Proteins, Interstitial
D016207:Cytokines; D000939:Epitopes; D005136:Eye Proteins; D010446:Peptide Fragments; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial