T-lymphocyte activation antigen CD80 (B7-1) (CD80)

T-lymphocyte activation antigen CD80, commonly known as B7-1, is a type I transmembrane glycoprotein belonging to the immunoglobulin superfamily (UniProt: P33681). It is primarily expressed on the surface of activated antigen-presenting cells, such as B cells, macrophages, and dendritic cells, where it provides the essential second signal for T-cell activation. CD80 serves as a critical costimulatory ligand that interacts with two distinct receptors on T-cells: CD28, which triggers T-cell activation and survival, and CTLA-4, which mediates inhibitory signals to maintain immune homeostasis (StatPearls: Abatacept). In the context of the TRICOM (TRIad of COstimulatory Molecules) vaccine platform, B7-1 is combined with ICAM-1 and LFA-3 to enhance the activation of tumor-specific T-cells (NCI Drug Dictionary). This synergistic combination is designed to overcome the poor immunogenicity of tumor cells and stimulate a robust immune response against cancer antigens (Hodge et al., 1999, Cancer Research). Therapeutically, CD80 is targeted by fusion proteins like abatacept and belatacept to treat autoimmune disorders and prevent transplant rejection by blocking costimulation. Conversely, in oncology, viral vectors are used to deliver the CD80 gene directly to tumor sites to promote an inflammatory microenvironment and enhance vaccine efficacy.

Other names

B7-1B7.1BB1LAB7CD28LGCD28LG1T-lymphocyte activation antigen CD80

CD80 acts as a costimulatory signal provider by binding to CD28 on T-cells, which is necessary for full T-cell activation following antigen recognition. It also binds to CTLA-4 with higher affinity, which serves to downregulate the immune response. In TRICOM-based immunotherapy, the exogenous expression of CD80, alongside ICAM-1 and LFA-3, works to lower the threshold of T-cell activation and increase the duration of the immunological synapse (Hodge et al., 1999, Cancer Research; UniProt: P33681).