Heat shock inhibits lipopolysaccharide-induced tissue factor activity in human whole blood

Abstract Background During gram-negative sepsis, lipopolysaccharide (LPS) induces tissue factor expression on monocytes. The resulting disseminated intravascular coagulation leads to tissue ischemia and worsens the prognosis of septic patients. There are indications, that fever reduces the mortality of sepsis, the effect on tissue factor activity on monocytes is unknown. Therefore, we investigated whether heat shock modulates LPS-induced tissue factor activity in human blood. Methods Whole blood samples and leukocyte suspensions, respectively, from healthy probands (n = 12) were incubated with LPS for 2 hours under heat shock conditions (43°C) or control conditions (37°C), respectively. Subsequent to further 3 hours of incubation at 37°C the clotting time, a measure of tissue factor expression, was determined. Cell integrity was verified by trypan blue exclusion test and FACS analysis. Results Incubation of whole blood samples with LPS for 5 hours at normothermia resulted in a significant shortening of clotting time from 357 ± 108 sec to 82 ± 8 sec compared to samples incubated without LPS (n = 12; p 0.05). Similarly, heat shock treatment of leukocyte suspensions abolished the LPS-induced tissue factor activity. Clotting time was 73 ± 31 s, when cells were treated with LPS (100 ng/mL) under normothermic conditions, and 301 ± 118 s, when treated with LPS (100 ng/mL) and heat shock (n = 8, p Conclusion Heat shock treatment inhibits LPS-induced tissue factor activity in human whole blood samples and isolated leukocytes.