Gram-positive and Gram-negative bacteria induce different cytokines from human peripheral blood mononuclear cells irrespective of taxonomic relatedness
Abstract number: p1182
Johansson S., Bigsten A., Hessle C., Wold A.
Upon bacterial stimulation tissue macrophages produce a variety of cytokines that orchestrate the immune response necessary to clear the infection. Earlier studies have shown that Gram-positive bacteria induce higher levels of IL-12, IFN-gamma and TNF from human peripheral blood mononuclear cells (PBMC) than Gram-negative bacteria, whereas Gram-negatives induce much more IL-6, IL-8 and IL-10 than Gram-positives. The aim of this study was to examine if this dichotomy is true for Gram-positive and Gram-negative bacteria irrespective of their position in the taxonomical system, and to relate cytokine production to phagocytosis.
PBMCs from healthy blood donors were incubated with 37 species of UV-inactivated Gram-positive and Gram-negative bacteria well spread in the taxonomical system. IL-12, TNF, IL-1beta, IL-6 IL-8 and IL-10 were measured in the supernatants after 24 h and IFN-gamma after 5 d with ELISA. Phagocytosis was studied in cytospin preparations after 30 min incubation.
Irrespective of their position in the phylogenetic tree, Gram-positive bacteria induced more IL-12, IFN-gamma and TNF than Gram-negatives, while Gram-negative bacteria were more potent stimulators of IL-6, IL-8 and IL-10 than Gram-positives. IL-1beta was induced in equal amounts from Gram-positive and Gram-negative bacteria. Production of IFN-gamma and TNF were strongly correlated, as were IL-6 and IL-8, and IL-6 and IL-10. There was no difference between Gram-positive and Gram-negative bacteria in the degree of phagocytosis. Nor were there any correlations between cytokine production and bacteria phagocytosed.
The results confirm that Gram-positive and Gram-negative bacteria trigger different cytokine patterns in human monocytes, irrespective of their genetic relatedness. Differences in composition of the bacterial wall are likely to account for these differences.
|Session name:||XXIst ISTH Congress|
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