CD8⁺ T cells express a T-helper 1-like phenotype after burn injury

Background. Previous studies suggest that CD8⁺ T cells are immunosuppressive after burn injury, but recent reports indicate that CD8⁺ T cells have several functions similar to CD4⁺ T cells, including the secretion of cytokines. This study uses HY male antigen in transgenic HY female mice to determine the antigen-specific response of activated CD8⁺ T cells after burn injury. Methods. HY TCR transgenic female mice underwent burn or sham injury. Seventy-two hours after the burn, splenocytes were stimulated with 20 μmol/L HY peptide for 16, 48, and 64 hours; cellular proliferation, intracellular interferon-γ and interleukin-2, and apoptosis were measured. Results. Burn injury significantly impaired proliferation to HY antigen (P ≤ .05). Activated CD8⁺ T cells from burned mice showed increased intracellular interferon-γ and interleukin-2 16 hours after stimulation compared with sham (P ≤ .05) and at no time was less than control mice. The percent of CD8⁺ T cells decreased with the time of stimulation but was not due to apoptosis by Annexin V staining. Conclusions. Activated CD8⁺ T cells express a T_H1-like phenotype after burn injury. This provides evidence that CD8⁺ T cells are not simply suppressive and that is consistent with data that CD4⁺ T cells are primed for a T_H1 response after burn injury.