Pulmonary epithelial T cells induced by viral infection express T cell receptors alpha/beta.

Cells were recovered from the lungs of mice by bronchoalveolar lavage before and after infection with respiratory syncytial (RS) virus. Uninfected mice yielded mostly macrophages, but after RS virus infection lymphocytes also appeared. Recovered cells were stained for CD4, CD8' and either CD3, T cell receptor (TcR) alpha/beta or TcR gamma/delta and analyzed by 3-color flow cytometry. Both the CD4+CD8- and CD4-CD8+ subpopulations stained uniformly for CD3 and TcR alpha/beta, while none stained for TcR gamma/delta. Of the CD4-CD8- cells, about 5% stained for CD3 and TcR alpha/beta during the first week after infection, although this figure increased during the second week. A small and variable fraction of this subset stained for TcR gamma/delta. These results oppose the view that lymphocytes expressing TcR gamma/delta predominate in initial epithelial immune responses to viral infections.