Figure 2. Mucosal CD4 T cell responses to pneumococci during aging and its relation with CAP rates.

(a) Mucosal CD4 T cell responses to pneumococcal peptide antigen display gradual age-related increases from early childhood until mid-20's and remain relatively constant until mid-life. Tonsil MNCs from subjects (n = 80) between the ages of 2 to 39 years and grouped into five age groups were assessed for their CD4 T cell proliferative responses to Strep. Pneumoniae Ply (circles, solid grey line of best fit), SPNT (square, dashed black line of best fit) and flu (triangle, black line of best fit) peptides, error bars show SEM. (b) Graph for data observed by Myles et al showing the trend (black crosses, dashed black line of best fit) of incidence rates of CAP per person/year in the UK at different age groups between 1991-2003 (n = 56332, R² = 0.97) in relation to the trend (grey circles, solid grey line of best fit) of mean total (to Ply and to SPNT) anti-pneumococcal CD4 T cell proliferative responses between the ages of 2 to 39 years old (R² = 0.93). Graph for CAP data was generated with permission from P.R. Myles.