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Mediators of Inflammation
Volume 12 (2003), Issue 3, Pages 173-178

mRNA expression and release of interleukin-8 induced by serum amyloid A in neutrophils and monocytes

1Departamento de Análises Clínicas e Toxicológicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, SP CEP 05508-900, Brazil
2Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
3Departamento di Patologia, Sezione di Patologia Generale, Universitá di Verona, Italy

Copyright © 2003 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The acute phase response is a systemic reaction to inflammatory processes characterized by multiple physiological adaptations, including the hepatic synthesis of acute-phase proteins. In humans, serum amyloid A (SAA) is one of the most prominent of these proteins. Despite the huge increase of serum levels of SAA in inflammation, its biological role remains to be elucidated, even though SAA is undoubtedly active in neutrophils. In a previous study, we reported that SAA induces the release of tumor necrosis factor-α, interleukin (IL)-1β and IL-8 from human blood neutrophils. Here, we extend our earlier study, focusing on the effect of SAA on neutrophil IL-8 transcription and on the signaling pathways involved. We demonstrate herein that SAA, in relatively low concentrations (0.4-100 μg/ml) compared with those found in plasma in inflammatory conditions, induces a dose-dependent release of IL-8 from neutrophils. The p38 mitogen-activated protein kinase inhibitor SB 203580 inhibits the IL-8 mRNA expression and the release of protein from neutrophils. The release of IL-8 from SAA-stimulated neutrophils is strongly suppressed by the addition of N-acetyl-l-cysteine, α-mercaptoethanol, glutathione, and dexamethasone. SAA also induces IL-8 expression and release from monocytes. In conclusion, SAA appears to be an important mediator of the inflammatory process, possibly contributing to the pool of IL-8 produced in chronic diseases, which may play a role in degenerative diseases.