Coagulation of Whole Blood Stimulates Interleukin-1β Gene Expression

To study interleukin (IL)-1β gene expression, reverse transcription-polymerase chain reaction was used on 25-μL whole blood samples from 11 healthy subjects. Coagulated and unclotted whole blood was compared. There was no evidence of IL-1β gene expression in any time zero samples (i.e., whole blood from which mRNA was immediately extracted) from 11 subjects, whereas a 388-bp band representing IL-lβ mRNA was detected in all coagulated samples. No mRNA for IL-1β was detected in EDTA-anticoagulated whole blood, although in these samples the addition of lipopolysaccharide as a positive control induced the expression of IL-1β. In time course studies on samples allowed to clot, mRNA for IL-1β was detectable after 30 min. These findings demonstrate that IL-1β gene expression is not present in circulating cells of healthy subjects and that coagulation is a stimulus for IL-1β gene expression. This may be a mechanism by which thrombosis produces inflammation and fever.