B7 family ligands (B7 family)

The B7 family ligands are a group of cell surface glycoproteins belonging to the immunoglobulin superfamily that are critical for the regulation of T-cell-mediated immune responses (Collins et al., 2005, Genome Biol). These ligands are primarily expressed on professional antigen-presenting cells and interact with receptors on the surface of T cells, such as the CD28 family, to provide necessary secondary signals (Ni and Dong, 2017, Mol Cancer). Depending on the specific ligand-receptor pair, these signals can be either costimulatory, promoting T-cell activation and proliferation, or coinhibitory, leading to T-cell exhaustion or tolerance (Pardoll, 2012, Nat Rev Cancer). Classic examples include B7-1 (CD80) and B7-2 (CD86), which bind to CD28 for activation or CTLA-4 for inhibition, and PD-L1 (B7-H1), which binds to PD-1 to suppress immune activity (Janeway et al., 2001, Immunobiology). In oncology, many tumors upregulate inhibitory B7 ligands to create an immunosuppressive microenvironment and evade detection by the immune system (Zou and Chen, 2008, Nat Rev Immunol). Conversely, dysregulation of these pathways is often implicated in the development of autoimmune diseases and chronic inflammation. Therapeutic strategies targeting this family include monoclonal antibodies that block inhibitory checkpoints (e.g., anti-PD-L1) and fusion proteins that block costimulation (e.g., CTLA-4-Ig) to treat cancer and autoimmune disorders, respectively (Sharpe and Freeman, 2002, Nat Rev Immunol).

Other names

B7-CD28 family ligandsB7 proteinsB7-like moleculesImmunoglobulin superfamily B7 ligands

Immune checkpoint inhibition (blocking inhibitory B7 ligands like PD-L1 to restore T-cell activity); Costimulation blockade (binding B7-1/2 to prevent CD28-mediated activation in autoimmunity); Antibody-dependent cellular cytotoxicity (ADCC) via targeting B7-H3 on tumor cells.