B7-H2/ICOSLG 是 T 细胞特异性表面受体 ICOS 的配体，是免疫反应的重要介质。该蛋白充当共刺激信号，促进 T 细胞增殖和细胞因子分泌，同时诱导 B 细胞增殖和分化为浆细胞。除了在免疫激活中的作用之外，B7-H2/ICOSLG 可能在炎症条件下介导局部组织反应中发挥关键作用。此外，它还通过共同刺激记忆 T 细胞功能来调节二次免疫反应。值得注意的是，在怀孕期间，B7-H2/ICOSLG 可能会影响母体 T 细胞的细胞因子谱，有利于免疫保护性 Th2 表型。此外，在体外观察到了 B7-H2/ICOSLG 与 CTLA4 的相互作用，突显了其参与复杂的免疫功能调节途径。
种属
Inducible co-stimulator ligand (ICOSL), also known as B7-H2, is a member of the B7 family of co-stimulatory molecules related to B7-1 and B7-2. It is a transmembrane glycoprotein with extracellular IgV and IgC domains and binds to ICOS on activated T cells, thus delivers a positive costimulatory signal for optimal T cell function. The structural features of ICOSL are crucial for its costimulatory function. The present study shows that ICOSL displays a marked oligomerization potential, resembling more like B7-1 than B7-2. B7-H2-dependent signaling may play an active role in a proliferative response rather than in cytokine and chemokine production. The CD28/B7 and ICOS/B7-H2 pathways are both critical for costimulating T cell immune responses. Deficiency in either pathway results in defective T cell activation, cytokine production, and germinal center formation.
