B-lymphocyte activation antigen B7-1 (CD80)

B-lymphocyte activation antigen B7-1 (CD80) is a type I transmembrane protein found on the surface of activated antigen-presenting cells (APCs) such as dendritic cells, B cells, macrophages, and some activated T cells[1][3][2]. It is a member of the immunoglobulin superfamily and serves as a key costimulatory ligand required for effective T cell activation. CD80 binds to CD28 on T cells to provide necessary secondary signals that drive T cell proliferation and cytokine production, or to CTLA-4 (CD152) for delivering inhibitory signals that downregulate immune responses[1][2][6]. Additionally, CD80 can interact in cis with PD-L1 on the same cell, competitively blocking PD-1 mediated immunosuppression[3]. Its regulation of T cell activation and tolerance makes it a critical immune checkpoint and an attractive therapeutic target in cancer immunotherapy and autoimmune disease. CD80 fusion proteins, CAR-T constructs, and other immunomodulators are being explored, but effective and safe clinical translation—especially outside hematologic malignancies—remains a challenge[3]. CD80 expression is used as a biomarker for immunological status, especially in lymphoid malignancies and in the context of immunotherapies[9][3].

Other names

B7-1CD80BB1B7cluster of differentiation 80T-lymphocyte activation antigen CD80B7 proteinactivation B7-1 antigen

Immune checkpoint modulation (co-stimulation or inhibition of T cell activation via CD28 or CTLA-4), Blocking immunosuppressive PD-L1/PD-1 signaling (via cis CD80/PD-L1 interactions), Enhancement of T cell response