预期应用
ELISA法定量测定人血清、血浆、细胞培养物上清或其它相关液体中LFA-3含量。
实验原理
本试剂盒应用双抗体夹心酶标免疫分析法测定标本中LFA-3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LFA-3抗原、生物素化的抗人LFA-3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LFA-3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 LFA-3 concentrations in cell culture supernates, serum, and plasma.
Introduction
T cells require a signal induced by the engagement of the T cell receptor and a “costimulatory” signal(s) through distinct T cell surface molecules for optimal T cell expansion and activation. Many cell-bound receptor-ligand pairs have now been shown to be involved in T cell co-stimulation including CD58/CD2 in humans and CD48/CD2 in mice and rats. CD58, also known as lymphocyte function-associated antigen (LFA-3), is a 210 amino acid protein that belongs to the CD2 family of the immunoglobulin superfamily.1 CD58 is widely expressed on hematopoietic and non-hematopoietic human tissue and has been found on leukocytes, erythrocytes, endothelial cells, epithelial cells and fibroblasts of human origin.2 No mouse or rat homolog of CD58 has as of yet been identified. CD58 has only one known ligand, CD2. CD2 is expressed on T cells, NK cells and Dendritic cells.2 - 4 CD2 ligation by CD58 has been shown to mediate T cell adhesion, T cell activation, T cell cytokine production and T cell and NK cells cytotoxic activity.1, 3, 5, 6 In dendritic cells, CD2 engagement increases MHC Class II, CD40, CD80, CD86, CD58 and CCR7 and induces IL-1β IL-12 cytokine secretion.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal
antibody specific for LFA-3 has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any LFA-3 present is bound by the immobilized antibody. An enzyme-linked monoclonal antibody specific for LFA-3 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 LFA-3 bound in the initial step. The color development is stopped and the intensity of the color is measured.
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