Burn injury induces a change in T cell homeostasis affecting preferentially CD4+ T cells.
Burn injuries are known to be associated with altered immune functions, resulting in decreased resistance to subsequent infection. In the present study, we determined the in vivo changes in T cell homeostasis following burn injury. Two groups of mice were used: a sham-burn group receiving buprenorphine as an analgesic and a burn group receiving buprenorphine and subjected to burn injury on 20% of the total body surface area. Results showed an important decrease in splenocytes following burn injury. This decrease persisted for 5 days and was followed, at day 10, by a 63% increase in number of cells. In vivo cell proliferation, as determined by the incorporation of 5-bromo-2'-dexoxyuridine, showed a significant increase of cycling splenocytes between days 2 and 10 after burn injury. The percentage of CD4+ and CD8+ T cells in the spleen was altered for 10 days after thermal injury. Analysis of naive (CD62Lhigh CD44low) and effector/memory (CD62Llow CD44high) T cells showed a percent decrease, independent of the expression of CD4 or CD8 molecules. However, early activation markers, such as CD69+, were expressed only on CD4+ T cells after a number of days following injury. Even with an activated phenotype, 10 days post-burn injury, CD4+ naive T cells significantly increased spontaneous apoptosis, detected by using a fluorescent DNA-binding agent 7-amino-actinomycin D. CD8+ T lymphocytes did not express early activation markers and were more resistant to apoptosis. Using purified T cells, we have shown unresponsiveness at day 10. Overall, these results demonstrate that mechanisms of T cell homeostasis were perturbed following burn injury. However, after 10 days, this perturbation persisted only in CD4+ T cells.
Patenaude
Julie
J
INRS-Institut Armand-Frappier, Pointe-Claire, Quebec, Canada.
D'Elia
Michele
M
Hamelin
Claudine
C
Garrel
Dominique
D
Bernier
Jacques
J
D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D017209:Apoptosis / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D002047:Buprenorphine / Q000627:therapeutic use; D002056:Burns / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D018450:Disease Progression; D006706:Homeostasis / Q000187:drug effects / Q000276:immunology*; D007239:Infections / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D014947:Wounds and Injuries / Q000276:immunology*
D015703:Antigens, CD; D002047:Buprenorphine