【项目简介】
CD5, also known as Leu-1, Ly-1, and T1, is a 67 kDa transmembrane glycoprotein in the scavenger receptor superfamily. Mature mouse CD5 consists of a 347 amino acid (aa) extracellular domain (ECD) with three scavenger receptor cysteine-rich (SRCR) domains, a 30 aa transmembrane segment, and a 93 aa cytoplasmic domain. Within the ECD, mouse CD5 shares 55% and 82% aa sequence identity with human and rat CD5, respectively. The 52 kDa ECD can be cleaved from the cell surface and circulates in the serum. CD5 has been shown to interact homophilically, with CD72 on B cells, and with beta-glucan components of fungal cell walls. CD5 expression on developing thymocytes is positively regulated by signaling through the T cell antigen receptor (TCR) and is up‑regulated on tolerized peripheral CD4+ cells. It inhibits TCR signaling and promotes T cell nonresponsiveness and survival. CD5 signaling inhibits the generation of regulatory T cells but promotes the development of Th17 cells. Within the B cell lineage, CD5 is expressed on B-1a cells, anergic B cells, and IL-10 producing regulatory B cells. Similarly to on T cells, it negatively regulates signaling through the B cell antigen receptor and supports peripheral B cell survival, anergy, and tolerance.
 
【检验原理】
本试剂盒采用双抗体夹心ELISA法。酶标微孔板上预包被有抗小鼠CD5抗体，当加入标准品和待测样本时，标准品和待测样本中的小鼠CD5会和该抗体结合。洗板后，游离的其他成分被洗去，加入辣根过氧化物酶标记的的抗小鼠CD5抗体可与被酶标板捕获的小鼠CD5结合，形成“包被抗小鼠CD5抗体+小鼠CD5+抗小鼠CD5抗体-HRP”免疫复合物。当加入TMB显色底物后，复合物上连接的HRP催化底物反应，生成蓝色产物，终止反应后变为黄色。在450nm处测定OD值，小鼠CD5浓度与OD450值之间呈正比，可通过绘制标准曲线求出标本中小鼠CD5的浓度。