Cutting Edge: A Single MHC Class Ia Is Sufficient for CD8 Memory T Cell Differentiation

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Abstract
Recent studies have suggested a role for MHC class Ib molecules in providing signals for memory T cell differentiation during the early phases of acute infection. To test this hypothesis, we assessed the development of effector and memory CD8 T cells in transgenic mice expressing a single chain H-2Dd/β2-microglobulin (β2M) fusion protein on a β2M-deficient background. These mice thus express a single MHC class Ia in the absence of all other β2M-dependent class Ia and Ib molecules. Following infection with a recombinant vaccinia virus expressing a known Dd-restricted epitope from HIV-1 gp160, the development of effector and memory cells CD8 T cells was comparable to control mice. Furthermore, these memory cells responded rapidly and robustly to antigenic restimulation. Therefore, we conclude that full CD8 memory differentiation requires only a single MHC class Ia chain, ruling out a requirement for MHC class Ib molecules in this process.