VIRUS-SPECIFIC CD8(-CELLS IN PRIMARY AND SECONDARY INFLUENZA PNEUMONIA() T)

Virus-specific CD8(+) effector T cells (eCTL) are enriched in the lung s of mice with primary influenza pneumonia, though later detection of memory T cells (mCTL) in the mediastinal lymph nodes (MLN) or spleen b y peptide-based staining protocols is at the limits of flow cytometric analysis. Respiratory challenge with an H3N2 virus months after H1N1 priming induces a massive recall response, which reduces virus titers 2-3 days earlier than in nave controls. Influenza-specific mCTL produc e interferon-gamma within 6 hr, but still take 4-5 days to localize to the infected respiratory tract. The delay reflects that the recall re sponse develops first in the MLN, which contains relatively few mCTL. The response to a subdominant epitope is less obvious after secondary challenge.