CD4^- CD8^- TCRα/β⁺ suppressor T cells demonstrated in mice 1 day after thermal injury

We have described previously that CD8⁺ CD11b⁺ TCRγ/δ⁺ type 2 T cells (BA-type 2 T cells) and suppressor macrophages (Sup-Mφ) are generated in spleens of mice 3 to 5 days (Sup-Mφ) and 4 to 9 days (BA-type 2 T cells) after thermal injury. In the present study, an additional suppressor T cell, characterized as CD3⁺ CD4^- CD8^- TCRα/β⁺ T cells (double negative suppressor T cells, DN Sup-T cells), was demonstrated in mice 1 day after thermal injury. DN Sup-T cells inhibited the proliferation of lymphocytes stimulated with allogeneic cells or a lectin in a mixed lymphocyte reaction, and produced both type 1 and type 2 cytokines (interferon-γ, interleukin-2, interleukin-4, and interleukin-10) when they were stimulated in vitro with anti-CD3 monoclonal antibody. These results suggest that DN Sup-T cells express phenotypic properties similar to natural suppressor cells and cytokine-producing profiles different from type 1 (Th1 cells and CTLs) and type 2 T cells (Th2 cells and CD8⁺ type 2 T cells). DN Sup-T cells may play a role on the burn-associated immunosuppression appearing in the acute phase of thermally injured individuals.