Identification of altered integrin alpha/beta chain expression on T cells from old mice infected with Mycobacterium tuberculosis.

During the natural aging process there is a gradual acquisition of T cell surface markers normally associated with cellular activation and memory. Because of this it is difficult to identify cells which are capable of responding to new antigenic challenge in older individuals, which therefore hinders the study of the immune response to infectious diseases. In this study we demonstrate that during natural aging there was an expansion in T cells that expressed the beta1 and beta2 integrins. Fewer CD8 T cells from old mice expressed beta7 integrins, however, they remained unchanged on CD4 T cells. In this study we also measured the expression of alphabeta integrin chains on the surface of T cells from mice of increasing age in response to an infection with Mycobacterium tuberculosis. We found that VLA-2 expression was increased on CD8 T cells from old mice however, the majority of integrins were unchanged in response to infection, in consequence of the increased expression of these molecules normally found in un-infected old mice. These findings are consistent with the hypothesis that age-associated changes occur in the number of cells that express molecules that allow T cells to traffic to inflammatory sites.