Hypothermia induces T-cell production of immunosuppressive cytokines.
BACKGROUND
Hypothermia is associated with increased postoperative infectious complications. We hypothesized that hypothermia suppresses the inflammatory response by altering T-cell cytokine production from a proinflammatory to an antiinflammatory profile, thus explaining the increased susceptibility to infectious complications associated with perioperative hypothermia.


METHODS
Forty rats were randomized to either a Hypothermia (30 degrees C) or Control (38 degrees C) group. Blood samples taken at baseline and after 8 h of thermoregulation were stimulated with phorbol 12-myristate 13-acetate and ionomycin. Interleukin (IL)-2 receptor expression and intracellular IL-10 production were measured using monoclonal antibodies and flow cytometry in CD4 and CD8 T cells. Differences in IL-10 production and IL-2 receptor expression for stimulated samples in the Hypothermia and Control groups were compared.


RESULTS
Stimulated CD4 cells demonstrated an antiinflammatory cytokine expression profile after hypothermia. Intracellular IL-10 production increased in the Hypothermia group but remained the same in the Control group (% change = 40 [3,87] and 2 [-36,26], respectively; P = 0.043). The increase in IL-2 receptor expression observed in the control group was suppressed after hypothermia (% change = 12[8,30] and 1 [-3,13], respectively; P = 0.026). We observed a greater increase in IL-10 production by CD8 cells from hypothermic animals than in those from control animals (% change = 41 [-8,90] and -4 [-40,5], respectively; P = 0.019). CD8 IL-2 receptor expression in hypothermic animals was similar to that of control animals (% change = 23 [-7,37] vs 25 [2,80], respectively; P = 0.32).


CONCLUSIONS
Hypothermia induced an antiinflammatory T-cell cytokine profile.
Lee
S L
SL
Department of Surgery, University of California-Davis, Health System, 2315 Stockton Boulevard, Sacramento, CA 95817-2214, USA.
Battistella
F D
FD
Go
K
K
D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D007035:Hypothermia / Q000276:immunology*; D016753:Interleukin-10 / Q000276:immunology*; D007376:Interleukin-2 / Q000276:immunology*; D008297:Male; D011183:Postoperative Complications / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013601:T-Lymphocytes / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
D007376:Interleukin-2; D016753:Interleukin-10