【项目简介】
CD28 (Cluster of Differentiation 28) is a disulphide-bonded glycoprotein belonging to the immunoglobulin (Ig) superfamily, and structurally consists of a single Ig V-like extracellular domain, a transmembrane domain and an intracellular domain. Mouse CD28 is constitutively expressed on the surface of all murine T cells and on developing thymocytes as disulfide-linked homodimers or as monomers. CD28 can binds the B7-1 and B7-2 ligand, and together perform important functions in the T and B cell response pathways. B7/CD28 family members, which can augment or antagonize T-cell receptor signaling, in the regulation of central and peripheral T-cell tolerance. CD28 is thus involved in T-cell activation, the induction of cell proliferation and cytokine production and promotion of T-cell survival.

【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人CD28抗体，当加入标准品和待测样本时，标准品和待测样本中的人CD28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人CD28抗体可与被酶标板捕获的人CD28结合，形成“包被抗人CD28抗体+人CD28+抗人CD28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，人CD28浓度与OD450值之间呈正比，可通过绘制标准曲线求出标本中人CD28的浓度。