High Temperature Affects Cytokine Release by Human Peripheral Blood Mononuclear Cells

Abstract

Background: Fever is one of the leading signs of the inflammatory process and it is one of the mechanisms that activate the immune system to defend the organism from various pathogens. For this goal, the peripheral blood mononuclear cells (PBMC) are among the first to be mobilized by triggering their capacity for phagocytosis and inflammatory cytokine production. However, their activation in the living organism is the outcome of several factors, including fever. The aim of the present work was to examine the effect of elevated temperature only on the capacity of human PBMC to produce inflammatory cytokines Methods: Stimulated and non-stimulated PBMC from healthy donors were treated with 37°C and 40°C for 4 and 24 hours. At the end of the incubation period the level of TNFα, IL-1β, IL-6, IL-10, IL-1ra, IL-2 and IFNγ was detected using ELISA kits. Results: Non-stimulated PBMC incubated at 37°C produced similar amounts of TNFα and IL-1β at 4 and 24 hrs. The expression of IL-6, IL-10 and IL-1ra was higher after 24 hrs as compared with that produced after 4 hrs. As for LPS-stimulated cells the production of all cytokines tested was increased significantly during 24 hrs of incubation except for the level of TNFα that did not differ significantly between 4 and 24 hrs of stimulation. Non-stimulated PBMC did not secrete detectable amounts of IL-2 or IFNγ, and that produced by PMA/ionomycin stimulated cells was significantly higher after 24 hrs of incubation as compared to 4 hrs. Elevation of the incubation temperature from 37°C to 40°C caused various degrees of inhibition in the generation of both pro- and anti-inflammatory cytokines. Conclusions: Exposure of unstimulated and stimulated PBMC to 40°C induced various degrees of inhibition in the production of both pro- and anti-inflammatory cytokines compared to cells incubated at 37°C. This observation may clarify the way the immune cells react in cases with fever.