Cutting edge: A single MHC class Ia is sufficient for CD8 memory T cell differentiation

Recent studies have suggested a role for MHC class A 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-2D(d)/beta 2-microglobulin (beta M-2) ion protein on a beta M-2-deficient background. These mice thus express a single MHC class Ia in the absence of all other beta M-2-dependent class Ia and A molecules. Following infection with a recombinant vaccinia virus expressing a known Did-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 la chain, ruling out a requirement for MHC class A molecules in this process.