Impaired specific CD8 T cell response with aging is not due to decreased expression of CD90 on TCR transgenic T cells

BACKGROUND: CD90 (Thy-1) is a small glycoprotein that is particularly abundant on the surface of mouse thymocytes and peripheral T cells, and is often used as a marker in adoptive transfer experiments to distinguish donor and recipient T cells with different CD90 subtypes. We have performed adoptive transfer experiments with T cell receptor transgenic (TCR Tg) mice to study the impaired CD8 T cell response with aging. FINDINGS: After stimulation with a CD8 T cell epitope, HA(518-524), the response of TCR Tg CD8 T cells from aged mice was decreased compared to the response of TCR Tg T cells from young mice. CD90 expression was also substantially decreased on the TCR Tg CD8 T cells of aged mice. However, the responses of CD90(hi) and CD90(low) CD8 T cells of the aged mice were similar in both early activation and proliferation, demonstrating that the impaired Tg T cell response with aging is not associated with the altered CD90 expression on CD8 T cells. CONCLUSIONS: The impaired Tg CD8 T cell response in aged mice is not due to age-associated changes in CD90 expression on Tg CD8 T cells.