Host immune response to influenza infection.

<p>(<b>A–E</b>) BALB/c mice were infected with PR8 (0.1LD₅₀) i.n. (<b>A</b>) Absolute numbers of neutrophils (solid line) and inflammatory mononuclear cells (dashed line) infiltrating the respiratory tract over time. (<b>B</b>) Absolute numbers of lymphocytes (T cells – gray dashes; B cells – black dashes; NK cells – solid lines) infiltrating the respiratory tract over time. (<b>C</b>) The number of lung antigen-specific CD8⁺ T cells was estimated following <i>in vitro</i> re-stimulation with influenza-infected target cells (P815) and analysis of IFNγ⁺CD8⁺ T cells via flow cytometry. (<b>D</b>) IFNγ content and (<b>E</b>) viral titer in sampled BAL fluid over time. Dashed line signifies limit of viral detection. (<b>A–E</b>) Two-three independent experiments (n = 2–4/expt) represented as mean ± SEM.