Effects of hypothermia and hyperthermia on cytokine production by cultured human mononuclear phagocytes from adults and newborns.
Level 5 - mechanism / opinion, no new human data
In vitro bench study using cultured human cells.
PubMed 11152570 · doi:10.1089/107999000750053708
What was done
Researchers compared the effects of moderate hyperthermia (40 degrees C) and hypothermia (32 degrees C) versus 37 degrees C on the kinetics of lipopolysaccharide (LPS)-induced cytokine expression (TNF-alpha, IL-1 beta, and IL-6) in cultured monocytes and macrophages isolated from human newborns and adults. Early (2 hours) and sustained (24 hours) cytokine concentrations in culture supernatants were measured.
What was found
At 40 degrees C, initial secretion rates of TNF-alpha and IL-1 beta were preserved, but the duration of secretion was shorter than at 37 degrees C. Supernatant concentrations at 24 hours under 40 degrees C were reduced by 18% to 50% for TNF-alpha and IL-1 beta, and 24-hour IL-6 was reduced by 26% to 29% in all cells except adult macrophages. At 32 degrees C, adult macrophages showed a 69% reduction in early TNF-alpha and a 65% reduction in early IL-6 secretion, but a 48% increase in 24-hour TNF-alpha compared with 37 degrees C. In adult monocytes at 32 degrees C, early IL-6 and IL-1 beta secretion decreased by 64% and 51%, respectively.
Why it matters
This study demonstrates that febrile temperatures produce a burst-and-suppression cytokine profile in human phagocytes, whereas hypothermia delays and prolongs cytokine exposure.
Limits
This is an in vitro study of cultured cells stimulated with LPS, which does not capture systemic physiological responses or clinical infection dynamics. The abstract does not report the donor sample size (n) or provide statistical significance metrics and variance data for the percentage differences.
Cited by
- contradicts Heating human subjects in a 39°C water bath elevates interferon and TNF levels, and monocytes exposed to LPS produced 10 times higher interferon at 39°C compared to lower temperatures.