Fig. 2.

T cell surface marker phenotyping for non-activated (a, b) and activated (c, d) T-helper and T-cytotoxic lymphocytes as assessed by CD3+CD4+, CD3+CD8+, CD4+CD25+, CD4+CD69+, CD4+CD44+, and CD8+CD44+ markers, respectively, measured as percentage of gated lymphocytes. Values indicate mean ± SEM. Significant difference: a, b, c P < 0.05 and d, e, f P < 0.01 between the control mice: young and middle-aged, middle-aged and old, old and young; *P < 0.05, **P < 0.01 between RSV and age-matched control mice