ARTHRITIS INDUCED BY PROTEOGLYCAN AGGRECAN G1 DOMAIN IN BALB C MICE -EVIDENCE FOR T-CELL INVOLVEMENT AND THE IMMUNOSUPPRESSIVE INFLUENCE OF KERATAN SULFATE ON RECOGNITION OF T-CELL AND B-CELL EPITOPES/

Our previous work showed that the proteoglycan aggrecan can induce ero sive polyarthritis and spondylitis in BALB/c mice, and that the G1 dom ain of the proteoglycan aggrecan (G1) is the arthritogenic region, In this study, two T cell epitopes residing on G1 within residues 70-84 ( peptide G5) and 150-169 (peptide G9) were identified using synthetic ; peptides and aggrecan-specific T cell lines, Two G1-specific T cell hy bridomas exclusively responded to peptide G5, When the G5-specific T c ell line was injected intraperitoneally into BALB/c mice, it induced a cute inflammatory arthritis in joints, but only in those that had been injected with the epitope recognized by these T cells, Furthermore, R e also demonstrate that the keratan sulfate chain(s) (KS) on G1 posses s immunosuppressive properties with respect tit T and B cell epitope r ecognition, T cell lines that recognize both G1 and peptide G5 show an increased response to G1 after KS is removed, Antibodies in hyperimmu ne sera of mice immunized with G1 show increased epitope recognition ( quantitative and qualitative) after KS removal before immunization, Th ese studies reveal that a T cell line specific to an epitope on the cl domain of aggrecan, also recognizing a corresponding mouse G1 epitope , calm induce arthritis by adoptive transfer and homing to the intraar ticular epitope, thereby implicating T cells in arthritis development caused by immunity to the G1 domain of aggrecan, Moreover, the presenc e of KS on G1 can inhibit arthritis development by suppressing T and B cell epitope recognition.