Baltz M L, Rowe I F, Caspi D, Turnell W G, Pepys M B
Clin Exp Immunol. 1986 Dec;66(3):701-8.
Serum amyloid A protein (SAA), an apolipoprotein of high density lipoprotein (HDL), is generally considered to be the precursor of AA protein, which forms the fibrils in reactive systemic amyloidosis in man and animals. This view is based on amino acid sequence identity between AA and the amino-terminal portion of SAA. However, in extensive and well-controlled studies of experimentally induced murine AA amyloidosis, we were unable to demonstrate a direct precursor-product relationship between SAA, in SAA-rich HDL preparations from acute phase or amyloidotic mouse or human serum, and AA protein in the amyloid deposits. This raises the possibility that SAA in its usual form, as an apolipoprotein of HDL synthesized during the acute phase response, may not be the major precursor of AA fibrils. The amyloidogenic forms of circulating SAA molecules may not be isolated during the preparation of HDL. Alternatively, particularly in the light of recent evidence that SAA mRNA is expressed in many different tissues throughout the body of appropriately stimulated animals, amyloidogenic SAA may be derived from sources other than the liver cells in which SAA-rich HDL is synthesized.
血清淀粉样蛋白A（SAA）是高密度脂蛋白（HDL）的一种载脂蛋白，通常被认为是AA蛋白的前体，AA蛋白在人和动物的反应性系统性淀粉样变性中形成纤维。这一观点基于AA与SAA氨基末端部分之间的氨基酸序列一致性。然而，在对实验诱导的小鼠AA淀粉样变性进行的广泛且严格控制的研究中，我们无法证明急性期或淀粉样变性小鼠或人血清中富含SAA的HDL制剂中的SAA与淀粉样沉积物中的AA蛋白之间存在直接的前体-产物关系。这就提出了一种可能性，即处于急性期反应期间合成的作为HDL载脂蛋白的正常形式的SAA可能不是AA纤维的主要前体。在制备HDL的过程中，可能无法分离出具有淀粉样变性的循环SAA分子形式。或者，特别是鉴于最近的证据表明，在适当刺激的动物体内，SAA mRNA在许多不同组织中表达，具有淀粉样变性的SAA可能来源于合成富含SAA的HDL的肝细胞以外的其他来源。
