Insights into the role of gammadelta T lymphocytes in the immunopathogenic response to thermal injury.
Studies have shown that cell-mediated immunity is markedly suppressed after thermal injury. T lymphocyte dysfunction and macrophage hyperactivity have been implicated as causative factors. Previous studies have primarily examined the effects of thermal injury on alphabeta T lymphocytes; however, the role of gammadelta T lymphocytes in the immune response after thermal injury is unclear. Therefore, wild-type mice and mice lacking the TCR delta gene (TCR delta-/-) were subjected to a third-degree scald burn and cell-mediated immune responses assessed at 7 days post-injury. TCR delta-/- mice had 75% mortality after burn injury compared with 25% mortality in the wild-type group. Plasma interleukin-6 (IL-6) levels were significantly elevated at 2, 4, and 18 h post-injury, whereas no difference was observed in tumor necrosis factor alpha (TNF-alpha) and prostaglandin E2 (PGE2) plasma levels. Plasma levels of these inflammatory mediators were similar in wild-type and TCR delta-/- mice post-injury. Splenic macrophage PGE2, IL-6, TNF-alpha, and IL-10 production was significantly increased in wild-type mice at 7 days post-injury, whereas macrophages from injured TCR delta-/- mice had a significantly attenuated capacity to produce IL-6 and TNF-alpha. In contrast, the increased release of PGE2 and IL-10 by macrophages post-injury was not reduced in TCR delta-/- mice. These results implicate a dual role for gammadelta T lymphocytes in the immunopathogenic response to burn injury: (1) they contribute to survival from the insult; and (2) they mediate the induction of a pro-inflammatory macrophage phenotype at 7 days post-injury. Thus, gammadelta T lymphocytes, in part through the modulation of macrophage activity, appear to contribute to the immune dysfunction after thermal injury.
Schwacha
M G
MG
Center for Surgical Research, Department of Surgery, Brown University School of Medicine and Rhode Island Hospital, Providence 02903, USA. mschwacha@lifespan.org
Ayala
A
A
Chaudry
I H
IH
D000818:Animals; D002056:Burns / Q000276:immunology* / Q000473:pathology; D002478:Cells, Cultured; D019675:Genes, T-Cell Receptor gamma; D006358:Hot Temperature; D007111:Immunity, Cellular; D007249:Inflammation / Q000276:immunology; D016753:Interleukin-10 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis / Q000097:blood; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D015850:Interleukin-6; D016692:Receptors, Antigen, T-Cell, gamma-delta; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10