Direct enumeration of M282-90 or M2127-135 epitope-specific CD8+ T lymphocytes. Groups of BALB/c mice were infected twice with RSV wild-type strain A2. Lung lymphocytes (A, B, and C) were harvested 8 days following the second infection and tested by flow cytometric analysis after staining with no tetramer (A), M282-90 tetramer (B), or M2127-135 tetramer (C). Dot plots illustrate results for total CD3+ lymphocytes as well as 20,000 CD8+ T lymphocytes. Numbers shown in the rectangular gate correspond to the percentages of CD8+ lymphocytes stained by the respective tetramers (tet). Data shown are representative of five experiments.