Repertoire analysis and new pathogenic epitopes of IRBP in C57BL/6 (H-2b) and B10.RIII (H-2r) mice.
OBJECTIVE
Interphotoreceptor retinoid binding protein (IRBP) is the major uveitogenic retinal antigen eliciting experimental autoimmune uveoretinitis (EAU) in mice. The most frequently used mouse strains are B10.RIII and C57BL/6, but to date only one uveitogenic epitope for each has been identified. The purpose of this study was to identify and characterize additional uveitogenic epitopes in B10.RIII and C57BL/6 mice and to compare epitope recognition in wild-type versus IRBP-deficient mice on both backgrounds.


METHODS
Mice were immunized with IRBP. Spleen cells were stimulated in culture with overlapping peptides representing the entire IRBP molecule, and lymphocyte proliferative responses were measured. Peptides determined to be immunodominant were used to immunize mice for EAU. Cytokine profile and proliferation of the CD4 versus CD8 subsets were analyzed for the most pathogenic peptides.


RESULTS
Two new major pathogenic epitopes were identified in WT C57BL/6 mice, residues 461-480 and 651-670. These epitopes induced EAU of severity similar to that induced by the previously known peptide, 1-20. Several other peptides elicited mild disease with lower incidence. Some peptides elicited EAU only in WT recipients of IRBP KO splenocytes. In the B10.RIII strain, two major new uveitogenic peptides were identified, 171-190 and 541-560, and several others elicited moderate disease. Unlike in C57BL/6 mice, adoptive transfer of WT B10.RIII with IRBP KO splenocytes did not reveal additional uveitogenic epitopes. Both CD4 and CD8 lymphocyte subsets proliferated to pathogenic peptides.


CONCLUSIONS
Several new pathogenic peptides of IRBP were identified in C57BL/6 and B10.RIII mice. Differences in epitope recognition between WT and IRBP KO mice were observed in C57BL/6 mice, but not in B10.RIII mice, suggesting more extensive culling of the repertoire in C57BL/6 mice by endogenously expressed IRBP.
Cortes
Lizette M
LM
Laboratory of Immunology, National Eye Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA.
Mattapallil
Mary J
MJ
Silver
Phyllis B
PB
Donoso
Larry A
LA
Liou
Gregory I
GI
Zhu
Wei
W
Chan
Chi-Chao
CC
Caspi
Rachel R
RR
D000595:Amino Acid Sequence; D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology* / Q000473:pathology; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D005136:Eye Proteins / Q000276:immunology*; D005260:Female; D006183:H-2 Antigens / Q000276:immunology*; D006239:Haplotypes; D016056:Immunodominant Epitopes / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology*; D012173:Retinitis / Q000276:immunology* / Q000473:pathology; D012177:Retinol-Binding Proteins / Q000276:immunology*; D014605:Uveitis / Q000276:immunology* / Q000473:pathology; D000099214:Retinol-Binding Proteins, Interstitial
D016207:Cytokines; D005136:Eye Proteins; D006183:H-2 Antigens; D016056:Immunodominant Epitopes; D010446:Peptide Fragments; D012177:Retinol-Binding Proteins; D000099214:Retinol-Binding Proteins, Interstitial