Influenza virus-specific T cells fail to reduce lung virus titres in cyclosporin-treated, infected mice.

Cyclosporin A (CsA) inhibited the function(s) of transferred influenza-specific K,D-restricted cytotoxic T cells, which led to clearance of virus in the lungs of influenza virus-infected mice. CsA had no effect on the migration of the transferred cells to the lungs. The pattern of migration and the number of cells recovered from the lungs were similar when cells were transferred into normal, untreated, infected or CsA-treated, infected mice. CsA had no effect on the in vitro expression of cytotoxic activity by the K,D-restricted cytotoxic T cells. These findings strongly suggest that the in vivo clearance of influenza virus by K,D-restricted cytotoxic T cells involves a lymphokine mechanism.