This immunoassay kit allows for the in vitro quantitative determination of human SAA concentrations in cell culture supernates, serum, plasma and other biological fluids.

 

Serum amyloid A (SAA) proteins are a family of apolipoproteins found predominantly associated with high-density lipoprotein (HDL) in plasma, with different isoforms being unequally expressed constitutively and in response to inflammatory stimuli. Although synthesized primarily in the liver, extrahepatic tissue_cellular expression of SAA has been widely documented. SAA has been linked to functions related to inflammation, pathogen defense, HDL metabolism, and cholesterol transport and thereby has been implicated in several pathological conditions including atherosclerosis, rheumatoid arthritis, Alzheimer s disease, and cancer. SAA is known best for its role during the acute phase response to an inflammatory stimulus such as infection, tissue injury, and trauma. During active inflammation the concentration of SAA in plasma can increase up to 1,***-fold within *4 h. It is believed that persistently high levels of SAA during chronic inflammation may contribute to the occasional development of the potentially fatal disease reactive amyloidosis (amyloid A (AA) amyloidosis). In AA amyloidosis, AA, an N-terminal (***6) fragment of SAA, frequently is found to form amyloid deposits in the liver, kidney, and spleen. However, the presence, in vivo, of full-length SAA in amyloid deposits and the ability of various SAA isoforms to form fibrils in vitro suggest that proteolytic cleavage may not be a prerequisite for AA deposition but rather a postdeposition event.

There is very limited structural information about SAA because of its inherent poor solubility in the apolipoprotein form. It is intriguing to understand how such a small protein is able to mediate or directly carry out such a wide range of functions related to inflammatory reaction and other hostdefense mechanisms. The various functions of SAA may be modulated by factors such as conformational changes induced by ligand binding or by the ability to adopt more than one oligomeric state. Deciphering the molecular basis of the functional and potentially pathological properties of SAA will require understanding its structure under various conditions.