Mapping immune responses to mRBP-3 1-16 peptide with altered peptide ligands.

PURPOSE Experimental autoimmune uveoretinitis (EAU) can be induced in C57BL/6 mice (I-A(b)) using human retinoid-binding protein-3 (hRBP-3, previously IRBP) residues 1-20. This study of a truncated murine peptide (mRBP-3 1-16) was conducted to determine its pathogenic potential and to characterize partially its interaction with specific T cells. METHODS After immunization with mRBP-3 1-16 or hRBP-3 1-20, EAU was assessed by immunohistochemistry. The immune response was assessed by tritiated thymidine incorporation and cytokine production analyzed by enzyme-linked immunosorbent assay (ELISA). T-cell receptor (TCR)- and major histocompatibility complex (MHC)-binding of mRBP-3 1-16 was studied by modeling and by using altered peptide ligands (APLs) and T-cell clones. RESULTS mRBP-3 1-16 induced EAU in C57BL/6 mice, with severity and kinetics comparable to that after immunization with hRBP-3 1-20. T cells taken from mice immunized with mRBP-3 1-16 had a Th1 phenotype and proliferated in response to reactivation with mRBP-3 1-16, hRBP-3 1-20, or mRBP-3 1-16 APLs. mRBP-3 1-16 APLs elicited at least five distinct patterns of reactivity when tested with the mRBP-3 1-16-reactive T-cell clones. CONCLUSIONS mRBP-3 1-16 immunizes and causes EAU in C57BL/6 mice. The studies using T-cell clones and APLs demonstrate that the immune response to mRBP-3 1-16 is drawn from a diverse population of antigen-specific T cells with a Th1 phenotype. Modeling and analysis of clones indicate that nonpathogenic T cells of an mRBP-3 1-16-reactive T-cell line recognize the peptide in a single register.