Human bone marrow: A reservoir for "enhanced effector memory" CD8 + T cells with potent recall function

Abstract

The role of human bone marrow (BM) CD8 + T cells in the immune response to viral Ags is poorly defined. We report here the identification and characterization of a functionally enhanced effector memory CD8 + T cell population (T EM) in the BM of patients undergoing total joint replacement for osteoarthritis. These BM-derived T EM differ strikingly from correlate cells in peripheral blood (PB), expressing elevated levels of CD27, HLA-DR, CD38, CD69, and unique patterns of chemokine receptors. Interestingly, while BM T EM have low levels of resting perform and granzyme B, these molecules evidence profound up-regulation in response to TCR stimulation resulting in enhanced cytotoxic potential. Moreover, compared with the T EM subset in PB, BM CD8 + T EM cells demonstrate a more vigorous recall response to pooled viral Ags. Our results reveal that human BM serves as a repository for viral Ag-spccific T EM with great therapeutic potential in vaccine development. Copyright © 2006 by The American Association of Immunologists, Inc.