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The functional influenza repertoire diminishes with age compared to the pool of influenza-specific CD8 T cells and the proportion of KLRG1hi CD57 hi influenza-specific T cell pre-vaccination inversely correlates with vaccine responsiveness.

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posted on 22.08.2011, 01:15 authored by Lisa E. Wagar, Beth Gentleman, Hanspeter Pircher, Janet E. McElhaney, Tania H. Watts

IFNγ positive populations were identified by influenza virus challenge as described in the methods. Influenza-specific CD8 T cell populations were identified by tetramer staining direct ex vivo for HLA-A2 donors. Comparisons between IFNγ and tetramer were made on a per-donor basis from pre-vaccination PBMC samples of young and older donors. (A) Ratio of IFNγ positive and tetramer positive CD8 T cells at pre-vaccination. (B) Comparison of peak antibody titers against seasonal H1N1 post-vaccination and total influenza-specific CD8 T cells out of total CD8 T cells present at pre-vaccination in young donors. (C) Correlation between peak H1N1 antibody titers induced from TIV vaccination and pre-existing tetramer+ CD8 T cells specific for influenza in older HLA-A2 donors. (D) The proportion of pre-existing CD8 T cells which were triple positive for KLRG1, CD57, and tetramer staining in 65+ donors inversely correlates with their peak H1N1 antibody titer production post-vaccination with TIV. (E) Lack of correlation between peak H1N1 antibody titers and frequency of KLRG1+CD57+ CD8 T cells in the total CD8 population.