预期应用
ELISA法定量测定大鼠血清、血浆、细胞培养物上清或其它相关液体中PlGF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PLGF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PLGF、生物素化的抗PLGF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PLGF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 PLGF concentrations in cell culture supernates, serum and plasma.
Introduction
A family of growth factors structurally related to VEGF has been identified and includes placenta growth factor (PlGF), VEGF-B, VEGF-C and VEGF-D, all contributing to the regulation of the vascular and/or lymphatic endothelium development. PlGF is a dimeric glycoprotein that, like VEGF, can bind with high affinity to the tyrosine kinase receptor vascular endothelial growth factor receptor 1 (VEGFR-1/Flt-1). PlGF/VEGF heterodimers have been isolated and shown to bind also to the VEGFR-2/KDR/Flk-1 receptor the major mediator of VEGF activities.
PlGF shares approximately 42% amino acid (aa) sequence identity with VEGF (53% within the PDGF region), and the two proteins share significant structural similarity. PlGF exists in at least 3 alternatively spliced forms: PlGF-1 (PlGF131), PlGF-2 (PlGF152), and PlGF-3 (PlGF203). Notable differences between these forms include the insertion of a heparin-binding domain in PlGF-2 that might result in increased association with the cell membrane or altered affinities for receptors. In mice, only the PlGF-2 ortholog has been described and shares 65% aa sequence identity with its human counterpart. As the name reflects, PlGF was first identified in human placenta where it is expressed prominently under normal conditions . Other tissues and cell types expressing PlGF include microvascular and human umbilical vein endothelia, bone marrow, uterine natural killer cells, and keratinocytes. It is upregulated under certain pathological conditions including wound healing, tumor formation, and preeclampsia.
PlGF has strong angiogenic properties in both fetal and adult life. PlGF overexpression results in a substantial increase in the number, branching and size of dermal blood vessels as well as in enhanced vascular permeability. Indeed, intradermally injected recombinant PlGF was able to induce vessel permeability in wild-type mice. The analysis of vascular endothelial growth factor receptor 1/flt-1 and vascular endothelial growth factor receptor 2/flk-1 indicates that the two receptors are induced in the skin endothelium of transgenic mice suggesting that both are involved in mediating the effect of overexpressed PlGF.
Test principle
This assay employs the quantitative sandwich enzyme immunoassay technique. A monoclonal
antibody specific for PLGF has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any PLGF present is bound by the immobilized antibody. An enzyme-linked monoclonal antibody specific for PLGF 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 PLGF bound in the initial step. The color development is stopped and the intensity of the color is measured.
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