B7 family costimulatory and coinhibitory ligands (B7 ligands)

Antigen-presenting cells (APCs) express a variety of surface ligands, most notably from the B7 family, which serve as critical regulators of T-cell activity and immune homeostasis (UniProt P33681, P42081, Q9NZQ7). CD80 (B7-1) and CD86 (B7-2) provide essential costimulatory signals by binding to CD28 on T cells, while also providing inhibitory signals through CTLA-4 (PubMed: 24011563). Programmed death-ligand 1 (PD-L1), another B7 family member, acts as a primary coinhibitory signal by binding to PD-1, leading to T-cell exhaustion and immune evasion, particularly in the tumor microenvironment (StatPearls: Immune Checkpoint Inhibitors). Therapeutic intervention targeting these ligands involves either blocking inhibitory pathways to enhance anti-tumor immunity or blocking costimulatory pathways to treat autoimmune diseases and prevent transplant rejection. For instance, CTLA-4-Ig fusion proteins like Abatacept bind CD80/86 to suppress T-cell activation in rheumatoid arthritis, while monoclonal antibodies like Atezolizumab block PD-L1 to restore T-cell mediated anti-tumor responses (PubChem: CID 11954310). These interactions are fundamental to the “two-signal” model of T-cell activation and are central to modern immunotherapy strategies.

Other names

B7-1B7-2B7-H1CD274CD80CD86B7 family

Competitive inhibition of costimulatory signals (CD80/86) or blockade of coinhibitory signals (PD-L1) to modulate T-cell activation and immune response.