Cells mediating delayed-type hypersensitivity in the lungs of mice infected with an influenza A virus

Effector cells that demonstrate delayed-type hypersensitivity (DTH) on transfer with antigen to naive mice can be recovered from the lungs of mice inoculated intranasally 6 days earlier with a lethal dose (usually 5x10(1)EID50) of influenza A virus. The activity recovered was proportional to the dose of virus instilled intranasally and the extent of lung consolidation observed. Active cells could also be recovered from the draining lymph nodes and from the peripheral blood. The effector cells were identified as T lymphocytes of Ly 1 phenotype and required I-region sharing between donor and recipient for activity to be elicited. They were cross-reactive within the A group of influenza viruses. Two experiments are reported in which immune cell preparations that expressed DTH activity but had very little cytotoxic T cell activity were transferred to mice inoculated 1 or 2 days earlier with a lethal dose of virus. The mice were not protected from death, and in both experiments, the recipient mice died more rapidly than the controls. These results contrast with earlier results in which cell preparations with high cytotoxic T-cell activity were shown to protect recipient infected mice from death.