本试剂盒应用双抗体夹心酶标免疫分析法测定标本中SP-B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SP-B抗原、生物素化的抗人SP-B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SP-B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 Surfactant protein B, SP-B concentrations in cell culture supernates, serum and plasma.
Introduction
Pulmonary surfactant is primarily responsible for lowering the surface tension at the air-liquid interface in the alveoli, a process that is essential for normal respiration. Pulmonary surfactant is a mixture of phospholipids and proteins, including four distinct surfactant-associated proteins (SPs), SP-A, SP-B, SP-C, SP-D. SP-B(8-9 kDa) and SP-C(4 kDa) are predominantly hydrophobic proteins that associate with lipids to promote the absorption of surfactant phospholipids and to reduce the surface tension in the alveoli. SP-A(28-36 kDa) and SP-D (43 kDa) are large multimeric proteins belonging to the family of calcium-dependent lectins, designated collectins, which contribute to the innate immune system. Both SP-A and SP-D have been shown to protect against microbial challenge through binding to the lipid components of the bacterial cell wall and facilitating the rapid removal of microbials.
SP-B is expressed in pulmonary adenocarcinomas with acinar, papillary, bronchioloalveolar, and solid growth patterns. Squamous cell and large cell carcinomas of the lung and nonpulmonary adenocarcinomas do not express SP-B.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A antibody specific for SP-B has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any SP-B present is bound by the immobilized antibody. An enzyme-linked antibody specific for SP-B 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 SP-B bound in the initial step. The color development is stopped and the intensity of the color is measured.
