预期应用
ELISA法定量测定大鼠血清、血浆或其它相关液体中可溶性CD40配体（sCD40L）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sCD40L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sCD40L抗原、生物素化的抗大鼠sCD40L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sCD40L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 Rat Soluble CD40 ligand（sCD40L）concentrations in serum and plasma.
Introduction
CD40 Ligand [CD40L, also known as CD154, gp39, TRAP (TNF-Related Activation Protein) or
TBAM (T-cell B-cell Activating Molecule)], a member of the TNF superfamily (TNFSF), is
a multi-functional ligand. Interaction between CD40 and CD40L is critical to the control of thymus-dependent humoral immunity and cell-mediated immune responses. The major component of the contact-dependent signal leading to B cell activation is CD40L. CD40L stimulates B cell secretion of immunoglobulin isotypes in the presence of cytokines. CD40L is a 39 kDa, 261 amino acid (aa) glycoprotein that can form homotrimers typical of other TNFSF members. Proteolytic cleavage can also produce soluble forms of CD40L. Activated T cells can express both a membrane-associated and a soluble form of CD40L (sCD40L).sCD40L lacks the transmembrane region and a portion of the extracellular domain, but contains the entire TNF- homology region. Both the membrane-bound and soluble forms of CD40L are active.The receptor for CD40L is CD40, a member of the TNF receptor superfamily (TNFRSF). Interaction of CD40L with CD40 not only induces proliferation of and isotype switching in B lymphocytes, but also mediates a broad variety of other immune and inflammatory responses. CD40 signaling has been linked with pathogenic processes of chronic inflammatory diseases, such as autoimmune diseases, neurodegenerative disorders, graft-versus-host disease, cancer, and atherosclerosis. The loss of interaction between CD40 and CD40L can result in impairment of T lymphocyte function, B lymphocyte differentiation, and monocyte function. CD40L is expressed primarily on activated CD4+ T cells, however, vascular endothelial cells, smooth muscle cells, macrophages, basophils, eosinophils, monocytes, dendritic cells, fibroblasts, and mast cells also express CD40L. Cytokine stimulation can increase surface levels and de novo synthesis of CD40L in certain cell types.Hyper-IgM syndrome (HIGM) is an immunodeficiency characterized by elevated concentrations of serum IgM and the absence of serum IgG, IgA and IgE. It is caused by mutations within the CD40L gene leading to defective expression on the membrane of activated T lymphocytes. B lymphocytes from HIGM patients express functional CD40 and respond normally to wild-type CD40L, but their T lymphocytes are unable to stimulate CD40 signaling pathways.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal antibody specific for SCD40L has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any SCD40L present is bound by the immobilized antibody. An enzyme-linked monoclonal antibody specific for SCD40L 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 SCD40L bound in the initial step. The color development is stopped and the intensity of the color is measured.
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