NP-specific CD8 T cells from aged mice exhibit altered Vβ usage. Young and aged C57BL/6 were intranasally infected with influenza virus and BAL was harvested on day 10 after infection. Panels on the left indicate the frequencies of CD8 T cells detected in the BAL of each individual mouse specific for the (A) NP (NP_366-374/D^b), (B) PA (PA_224-233/D^b), or (C) PB1 (PB1_703-711/K^b) epitopes. Panels on the right indicate TCR Vβ chain usage of epitope-specific CD8 T cells determined using the indicated anti-Vβ antibodies. Each symbol identifies an individual mouse. Closed symbols represent individual young mice (n = 3), and open symbols represent individual aged mice (n = 5).