Family Medicine: Care for A Lifetime

Abstract

Although the pathogenesis of collagen-induced arthritis (CIA), a model of rheumatoid arthritis, is mediated by both collagen-specific CD4⁺ T cells and Ab specific for type II collagen (CII), the role of CII-specific T cells in the pathogenesis of CIA remains unclear. Using tetrameric HLA-DR1 with a covalently bound immunodominant CII peptide, CII_259–273, we studied the development of the CII-specific T cell response in the periphery and arthritic joints of DR1 transgenic mice. Although the maximum number of DR1-CII-tetramer⁺ cells was detected in draining lymph nodes 10 days postimmunization, these T cells accounted for only 1% or less of the CD4⁺ population. After day 10, their numbers gradually decreased, but were still detectable on day 130. Examination of TCR expression and changes in CD62L, CD44^high, and CD69 expression by these T cells indicated that they expressed a limited TCR-BV repertoire and had clearly undergone activation. RT-PCR analysis of cytokine expression by the tetramer⁺ T cells compared with tetramer⁻ cells indicated the tetramer⁺ cells expressed high levels of Th1 and proinflammatory cytokines, including IL-2, IFN-γ, IL-6, TNF-α, and especially IL-17. Additionally, analysis of the synovium from arthritic paws indicated that the same CD4⁺/BV8⁺/BV14⁺/tetramer⁺ T cells were present in the arthritic joints. These data demonstrate that although only small numbers of CII-specific T cells are generated during the development of CIA, these cells express very high levels of cytokine mRNA and appear to preferentially migrate to the arthritic joint, indicating a potential direct role of CII-specific T cells in the pathogenesis of CIA.