Stains & CD markers
Serum amyloid A (SAA)
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Serum amyloid A
Serum amyloid A (SAA)
Author: Sheren Younes, M.D., Ph.D.
Editorial Board Member: Lauren N. Stuart, M.D., M.B.A.
Last author update: 1 September 2017
Last staff update: 26 February 2024
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Serum amyloid A
Table of Contents
Background | Structure | Role of SAA in pathogenesis of different diseases | Role in pathology | Microscopic (histologic) imagesCite this page: Younes S. Serum amyloid A (SAA). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsserumamyloida.html. Accessed April 18th, 2024.
Background
- Acute phase protein, which has diagnostic, therapeutic and prognostic implications in a wide variety of diseases
- First recognized in serum with its cross reactivity with antisera to amyloid AA of secondary amyloid; both proteins have precursor / product relationship
Structure
- 104 AA residues
- N terminal is usually 76 residues identical to protein AA
- Four genes encode SAA isoforms (SAA1, SAA2, SAA3 and SAA4); it spans 10 kb within the p15.1 region of chromosome 11
- Each gene encodes a different protein
- Synthesized in liver
- In blood, SAA is associated with HDL in acute phase response
- Expressed variants of protein and mRNA in different tissues, not only liver, also breast, colon, adipocytes, brain (Curr Med Chem 2016;23:1725)
Role of SAA in pathogenesis of different diseases
- Plays a role in inflammation
- Role in atherosclerosis: SAA1 and SAA2 promote early atherogenesis (Curr Opin Lipidol 2016;27:531); one of the early markers of preclinical atherosclerosis (Vasa 2015;44:247)
- Increased plasma level of SAA in type II diabetes (Clin Biochem 1994;27:469)
- Produced in the brain of patients with Alzheimer disease (Neurosci Lett 1997;225:73)
- One of the rheumatoid arthritis biomarkers (J Med Life 2016;9:144); mRNA concentration increases in synovial tissue of RA patients compared to normal (Arthritis Rheum 2004;50:1788)
- SAA mRNA is increased in adipocytes in obesity (J Clin Endocrinol Metab 2005;90:2233)
- May promote COPD (Am J Respir Crit Care Med 2013;188:179)
- Potential biomarker of neonatal sepsis (Microb Pathog 2017;107:234)
- Predicts severity of acute pancreatitis (Crit Rev Clin Lab Sci 2015;52:273)
- SAA role in cancer
- May be involved in pathogenesis of myeloma (J Cell Biochem 2008;103:994) and gastric cancer (Ann Surg Oncol 2007;14:84)
- Predicts prognosis of neoplasia (J Clin Pathol 1986;39:794)
- Circulating SAA is associated with prognosis in osteosarcoma patients (Pediatr Blood Cancer 2017 May 24 [Epub ahead of print])
- Serum levels of SAA is upregulated in glioblastoma (J Neurooncol 2017;132:383)
Role in pathology
- SAA staining is fairly specific for sarcoidosis (Respir Med 2017;126:1)
- SAA is associated with earlier stages of chronic hepatitis (Histopathology 2016;69:937)
- Can be used in combination with other markers to classify hepatocellular adenoma into groups (Front Med (Lausanne) 2017;4:10)
Microscopic (histologic) images
Images hosted on other servers:
SAA in hepatic adenoma (fig. H)
