Costimulatory molecule CD80 (CD80)

Costimulatory molecule CD80 (B7-1) is a type I transmembrane glycoprotein of the immunoglobulin superfamily and a major member of the B7 family of co-stimulatory ligands. It is predominantly expressed on antigen-presenting cells—such as dendritic cells, B cells, monocytes/macrophages, and activated T cells—and is essential for the full activation of naive T cells. CD80 provides the second signal in T-cell activation by binding to CD28 on T-cells to promote immune activation, proliferation, cytokine production (notably IL-2), and survival. Alternatively, it can bind CTLA-4 (CD152) with higher affinity, delivering inhibitory signals to prevent overactivation and maintain immune tolerance. CD80 also interacts with PD-L1, modulating the balance between T-cell activation and inhibition within the tumor microenvironment. Its expression and function are implicated in cancer immunology, transplantation, infection, and autoimmune disorders, making it a prominent therapeutic target for immunomodulation and immune checkpoint blockade. Therapeutics targeting CD80 or its pathways include fusion proteins (abatacept, belatacept, CD80-Fc) and immune checkpoint inhibitors.

Other names

B7-1B7BB1Cluster of Differentiation 80

Blockade of CD80-CD28 or CD80-CTLA-4 interaction to modulate immune responses Fusion protein (e.g., CD80-Fc) acts as co-stimulatory ligand to activate T-cells or block inhibitory checkpoints Competitive inhibition of T-cell inhibitory signaling (e.g., PD-L1 binding)