In vivo proliferation of naive and memory influenza-specific CD8(+) T cells

The virus specific CD8(+) T cell response has been analyzed through the dev elopment, effector, and recovery phases of primary and secondary influenza pneumonia, Apparently, most, if not all, memory T cells expressing clonotyp ic receptors that bind a tetrameric complex of influenza nucleoprotein (NP) (366-374) peptide+H-2D(b) (NPP) are induced to divide during the course of this localized respiratory infection. The replicative phase of the recall r esponse ends about the time that virus can no longer be recovered from the lung, whereas some primary CD8(+)NPP(+) T cells may proliferate for a few m ore days, The greatly expanded population of CD8(+)NPP(+) memory T cells in the lymphoid tissue of secondarily challenged mice declines progressively in mean prevalence over the ensuing 100 days, despite the fact that at leas t some of these lymphocytes continue to cycle, The recall of cell-mediated immunity thus is characterized by massive proliferation of the antigen-spec ific CD8(+) set, whereas the extent of lymphocyte turnover in the absence o f cognate peptide is variable, at a low level, and can be influenced by int ercurrent infection.