Differential effects of in vitro and in vivo hyperthermia on the production of interleukin-10.
OBJECTIVE
To determine whether hyperthermia activates an anti-inflammatory response.


METHODS
A prospective study.


METHODS
Heatstroke Center, Makkah, and King Faisal Specialist Hospital, Riyadh, Saudi Arabia.


METHODS
Twenty-five heatstroke patients pre-cooling (rectal temperature 42.4 +/- 0.8 degrees C) (group 1) and 13 normothermic heat-stressed subjects were studied (group 2). Twelve of the 25 heatstroke patients were also studied post-cooling (group 3). Mononuclear cells from six healthy blood donors resting at 24 degrees C were used for in vitro study.


METHODS
Mononuclear cells were cultured at a concentration of 1 x 10(6)/ml without and with lipopolysaccharide (LPS) added at concentration of 10, 100, and 1000 ng/ml. The cells were incubated for 24 h at 37, 39, 41, and 43 degrees C. ELISA was used to measure IL-10 in the supernatant and plasma from heatstroke and heat-stressed subjects.


RESULTS
All patients in group 1, 40% of group 2, and 37% of group 3, showed elevation of IL-10 (1289 +/- 2519, 248 +/- 393, and 172 +/- 226 pg/ml, respectively) compared with normal control levels, (< 100 pg/ml) P < 0.05. IL-10 level on admission did not correlate with degree of hyperthermia. During 24 h incubation at 37 degrees C without LPS, no IL-10 was detected, whereas with 10 ng/ml LPS, monocytes released 658 +/- 291 pg IL-10/10(6) cells. At 39 degrees C and 41 degrees C IL-10 release was decreased to 225 +/- 114, and 245 +/- 90 pg/10(6) cells, respectively; and was completely inhibited at 43 degrees C (67 +/- 10 pg/10(6) cells), P < 0.0001.


CONCLUSIONS
Heat-stress with and without hyperthermia is associated with anti-inflammatory response in vivo. However, it does not seem to be the direct effect of heat on monocytes, suggesting that other environmental or genetic factors may be involved.
Bouchama
A
A
Department of Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia. abouchama@hotmail.com
Hammami
M M
MM
Al Shail
E
E
De Vol
E
E
D000704:Analysis of Variance; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005334:Fever / Q000276:immunology*; D018882:Heat Stress Disorders / Q000175:diagnosis / Q000276:immunology*; D018883:Heat Stroke / Q000175:diagnosis / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D016753:Interleukin-10 / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000276:immunology*; D008070:Lipopolysaccharides; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric
D008070:Lipopolysaccharides; D016753:Interleukin-10