γδ T Cells from Influenza-Infected Mice Develop a Natural Killer Cell Phenotype Following Culture

Bronchoalveolar lavage (BAL) populations recovered from mice with secondary influenza pneumonia contain γδ T cell receptor (TCR)+ NK1.1- lymphocytes and γδTCR-NK1.1+ natural killer (NK) cell populations. Stimulating the CD4-8- component of the BAL with a monoclonal antibody to CD3ϵ and rIL-2 leads to the emergence of substantial numbers of CD4-8-γδTCR+NK1.1+ and CD4-8-αβTCR+NK1.1+ lymphocytes. The NK1.1+ γδ T cells are potent cytotoxic effectors, causing much higher lysis of YAC-1 target cells than the γδTCR+NK1.1- lymphocytes that are present concurrently, CD4+ and CD8+ αβ T cells cultured in the same way express little (if any) NK1.1. The possible functional role of NK1.1+ γδ T cells is discussed.