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RACTIVITY | Human |
SENSITIVITY | <1.1 ng/mL |
ASSAY RANGE | 5 ng/mL-16 μg/mL |
REAGENTS PROVIDED | SAA MICROTITER PLATESAA CONJUGATESAA STANDARDCALIBRATOR DILUENT ISAA QUALITY CONTROL SAMPLE ISAA QUALITY CONTROL SAMPLE IIWASH BUFFER (20X)SUBSTRATE ASUBSTRATE BSTOP SOLUTION |
INTENDED USE
This Human SAA ELISA Kit is to be used for the in vitro quantitative determination of human serum amyloid A (SAA) concentrations in serum, plasma, and other biological fluids. This kit is intended FOR LABORTORY RESEARCH USE ONLY and is not for use in diagnostic or therapeutic procedures.
INTRODUCTION
Serum Amyloid A (SAA) is an acute-phase protein. During acute events, the rise in SAAlevels is the most rapid and intense increase of all acute phase proteins. Cytokines such as IL-1, IL-6, and TNF are considered mediators of SAAprotein synthesis. They stimulate hepatocytes in the liver to produce and release SAAinto the bloodstream. When elevated above normal levels SAAis almost exclusively bound to High Density Lipoproteins (HDL), causing SAAto behave like an apolipoprotein - a protein moiety occurring in plasma lipoprotiens. SAAcirculates at trace levels (1-7 µg/mL) during normal conditions; however 4-6 hours after inflammatory stimulus, SAAlevels can increase by as much as 1000 fold to remarkably elevated levels (500-1000 µg/mL), thus making SAAa sensitive marker. 1,2
Structural analysis revealed this 104 amino acid (a.a.) polypeptide in its native state has a molecular mass of 12-14 kDa. Serum amyloid A is the serum precursor of amyloid A (AA) protein (8.5 kDa), which is formed when the first 76 amino acids of amyloid A protein are cleaved. The human SAAprotein is polymorphic being made up of a family of several related proteins (SAA1 to SAA4). SAA genes are located on chromosome 11p.1 SAA1 and SAA2 are similar genes, which differ by 7 amino acids or more, and encode acute-phase SAAs. SAA3 appears to be a pseudogene and is substantially different from the others. SAA4 does not vary significantly during the acute phase response and is an isoform that is present on HDL during homeostasis.3,4 Each of the acute phase proteins have a unique function in modulating host immune responses but the role of SAA remains unclear. It is known that HDL inhibits SAA"s function. This suggests that SAA needs to be released from HDL complexes in order to become active.5 It was reported that SAA may have an important pro-inflammatory and immunostimulating role by recruiting neutrophils, monocytes, and T-lymphocytes into inflammatory lesions.5,6 As a result of SAA"s association with HDL, a role in cholesterol metabolism has been proposed. SAA, after dissociation from HDL, may play a role in cholesterol transport at local tissues sites during inflammation by binding cholesterol.2,7
High levels of SAAcan be seen in patients with acute and chronic inflammation. Secondary amyloidosis may develop as a result prolonged or repeated inflammatory conditions in which SAAlevels remain elevated. This progressive, fatal condition is characterized by a gradual loss of organ function, in which fibrils are deposited in peripheral tissues and major organs. The fibrils are caused by the incomplete degradation of SAAin which the AA fragment (8.5 kDa) from the original SAAprotein has been enzymatically cleaved. Measuring SAAlevels in these patients may be a useful indicator of degree of inflammation and response to therapy. Inflammatory disorders such as rheumatoid arthritis, juvenile arthritis, ankylosing spondylitis, familial mediterranean fever, progressive sclerosis as well as chronic infections such as tuberculosis and osteomyelitis are predisposed to developing amyloidosis.8,9 Measuring SAA levels is also significant in determining pulmonary inflammation in patients with cystic fibrosis,10 diagnosing and predicting renal allograft rejection,11 determining anti-microbial therapy response in urinary tract infections,12 opportunistic infections in AIDS,13 inflammation in acute viral infections,14 biocompatiblility of hemodialysis,15 tissue damage in post-acute myocardial infarction, 17 and the outcome in severe unstable angina.16 Also, a differential diagnosis of inflammatory disease may be employed by measuring SAA levels. Acute viral infections may be distinguished from bacterial infections by determining SAA levels.14-17 It may be useful to confirm diagnosis of acute viral diseases if SAA is assayed at the same time as C-reactive protein, which is a useful inflammatory marker for bacterial infections and does not rise during viral disease.16
This SAA ELISA is a 2.5-hour solid phase immunoassay readily applicable to measure SAA in serum, plasma, and other biological fluids in the range of 0 to 16mg/mL. It showed no cross reactivity with other cytokines tested. This SAA ELISA is expected to be effectively used for further investigations into the relationship between SAA and the various conditions mentioned.
Additional
Additional Information
| Product Specificity | Human SAA ELISA Kit (2nd Generation) |
|---|---|
| Application | Refer to Insert |
| Size | 96 wells |
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请赐教！
所以一个细菌或病毒可以有很多的抗原。
荚膜（capsule）是某些细菌在生长繁殖过程中分泌的一层黏液性物质，包围在细胞壁外，通常这种黏液层厚度小于0.2μm，成分是多糖或多肽，只有在营养丰富时或在动物体内，细菌才产生这种半抗原性质的黏液性物质。它具有保护菌体免受巨噬细胞等的捕捉和吞噬，因而具有抗吞噬抗消化、侵袭力强、与致病性关系密切等特点。像肺炎球菌、炭疽杆菌等都有这类荚膜。有些细菌的荚膜层较薄，小于0.2μm，称为微荚。
像链球菌的M蛋白、伤寒杆菌的Vi抗原、大肠杆菌的K抗原等都属于这类微荚膜。
荚膜是某些细菌在细胞壁外包围的一层粘液性物质，一般由糖和多肽组成，是细菌的一种特殊结构。
作用：
①抗吞噬作用：荚膜因其亲水性及其空间占位、屏障作用，可有效抵抗寄主吞噬细胞的吞噬作用。
②黏附作用：荚膜多糖可使细菌彼此间粘连，也可黏附于组织细胞或无生命物体表面，是引起感染的重要因素，具有荚膜的S-型肺炎链球菌毒力强，有助于肺炎链球菌侵染人体；废水生物处理中的细菌荚膜有生物吸附作用，将废水中的有机物、无机物及胶体吸附在细菌体表面上。
③抗有害物质的损伤作用：处于细菌细胞最外层，荚膜犹如盔甲可有效保护菌体免受或少受多种杀菌、抑菌物质的损伤，如溶菌酶、补体等。
④抗干燥作用：荚膜多糖为高度水合分子，含水量在95%以上，可帮助细菌抵抗干燥对生存的威胁。
⑤当缺乏营养时，荚膜可被利用作碳源和能源，有的荚膜还可作氮源。
颗粒型抗原,除了有细菌、红细胞、螺旋体等天然颗粒型抗原,还有吸附有可溶性抗原的非免疫相关颗粒.
颗粒性抗原光镜下可见，比如细菌性抗原、红细胞抗原等；而可溶性抗原在光镜下不可见，如组织浸出液、细菌毒素、蛋白质分子等。
它们不等同于完全抗原和不完全抗原。完全抗原具有免疫原性和抗原性，而不完全抗原只具有抗原性。完全抗原可以是颗粒性抗原，亦可是可溶性抗原，而不完全抗原一般只能是可溶性抗原，不会是颗粒性抗原。
