Functional analysis of the TCR alpha- beta+ cells that accumulate in the pneumonic lung of influenza virus-infected TCR-alpha-/- mice.

In mice homozygous (-/-) for a targeted TCR-alpha gene disruption, some thymocytes express a cell-surface TCR-beta chain on the cell surface in the absence of a TCR-alpha chain, and a few CD4+CD8- TCR-alpha-beta+ cells accumulate in the peripheral lymphoid organs. We have infected these mutant mice with an influenza A virus to show that large numbers of TCR-beta+ cells (most of which are CD4+) can be retrieved from the pneumonic lung. Both freshly isolated TCR-alpha-beta+ cells and TCR-alpha-beta+ hybridoma cell lines derived from influenza virus-infected mutant mice respond appropriately to stimulation with anti-CD3 epsilon or the Mls-1 superantigen. It thus seems that CD4+ TCR-alpha-beta+ cells in the peripheral lymphoid organs of TCR-alpha mutant mice can signal through their TCR surface complex. However, there are no indications that CD4+ TCR-alpha-beta+ lymphocytes can either recognize a complex between MHC and influenza virus peptide or act as effector or Th cells. The existence and function of such cells in wild-type mice remains to be established.