Prominent usage of V beta 8.3 T cells in the H-2Db-restricted response to an influenza A virus nucleoprotein epitope.

The spectrum of TCR usage has been analyzed for virus-specific CD8+ T cells isolated from the regional mediastinal lymph modes and from the lung by bronchoalveolar lavage (BAL) of C57BL/6 (B6) mice with influenza pneumonia. Lymphocytes were recovered during the acute phase of the primary response in mice infected with an H3N2 (A/HKx31) virus, or in immune animals that were secondarily challenged with an H1N1 virus (A/PR8). Cells taken directly from the BAL of infected mice exhibited an increase in the frequency of V beta 8.3+/CD8+ T cells. In addition, 20 to 50% of proliferating CD8+ T cells in the mediastinal lymph nodes and BAL populations stimulated in vitro with A/HKx31 were V beta 8.3 TCR+. These observations indicated that the V beta 8.3+/CD8+ T cells were specifically involved in the inflammatory process during influenza infection. However, in vivo depletion of V beta 8+ T cells in CD4-depleted mice did not adversely affect viral clearance, suggesting that other CD8+ T cells can compensate for the absence of these cells. The spectrum of TCR usage was also analyzed for influenza-specific T cell hybridomas derived from freshly isolated BAL of mice with pneumonia. Many of these T cell hybridomas were V beta 8.3+, although other TCR V beta elements were used. All of the V beta 8.3+ hybridomas recognized the H-2Db-restricted NP epitope, 365-380. Although the V beta 8.3 TCR contain similar TCR D beta and J beta elements, V alpha usage was surprisingly variable. Therefore, recognition of this particular epitope was dominated by the beta-chain of the TCR. We conclude that the murine CD8+ response to influenza A virus infection of B6 mice is limited in terms of the diversity of the responding T cells. However, there is significant plasticity in the CD8+ response, which readily compensates for the absence of the dominant T cell population.