Rheumatoid Arthritis (RA) is a chronic inflammatory disease affecting 1% of the population. Although CD4+ T-cells have been associated with the pathogenesis of RA, there is evidence that CD8+ T-cells may be important as well. The goal of our research is to identify the function of CD8+ T-cells in RA by studying peripheral blood and synovial membranes of RA patients, as well as the murine model of collagen-induced arthritis. To assess function, we will examine the phenotype and cytokine profile of CD8+ T-cells in the peripheral blood and synovial membrane of RA patients. Additionally, we will examine the role of CD8+ T-cells in collagen-induced arthritis through T-cell depletion studies.