本试剂盒应用双抗体夹心酶标免疫分析法测定标本中sIgA水平。用纯化的抗体包被微孔板，制成固相抗体，往包被单抗的微孔中依次加入sIgA抗原、生物素化的抗人sIgA抗体、HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的sIgA呈正相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the specific measurement of human soluble Immunoglobulin A, sIgA concentrations in cell culture supernates, saliva,serum, and plasma.
Introduction
Immunoglobulin A (IgA) is an antibody and, in its secretory form, is the main immunoglobulin found in mucous secretions, including tears, saliva, colostrum, intestinal juice, vaginal fluid and secretions from the prostate and respiratory epithelium. It is also found in small amounts in blood. Because it is resistant to degradation by enzymes, secretory IgA can survive in harsh environments such as the digestive and respiratory tracts, to provide protection against microbes that multiply in body secretions.IgA does not activate complement, and opsonises only weakly. Its heavy chains are of the type α.
Human Immunoglobulin A (IgA) represents about 15% to 20% of immunoglobulins in the blood, although Human Immunoglobulin A (IgA)is primarily secreted across the mucosal tract into the stomach and intestines. This prevents microbes from binding to epithelial cells in the digestive and respiratory tracts. Human Immunoglobulin A (IgA)helps to fight against pathogens that contact the body surface, are ingested, or are inhaled.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal
antibody specific for sIgA has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any sIgA present is bound by the immobilized antibody. An enzyme-linked polyclonal antibody specific for sIgA is added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of sIgA bound in the initial step. The color development is stopped and the intensity of the color is measured.
