Antigen-presenting cell co-stimulatory complex (CD80, CD86, and MHC) (APC (CD80/CD86/MHC))

Antigen-presenting cells (APCs), such as dendritic cells and macrophages, are fundamental to the adaptive immune system, serving to process and present antigens to T cells. This interaction occurs via the Major Histocompatibility Complex (MHC) on the APC binding to the T-cell receptor (TCR), providing the first signal for activation (NIH: GeneID 3105). However, full T-cell activation and proliferation require a second, co-stimulatory signal, which is primarily delivered by the binding of CD80 (B7-1) and CD86 (B7-2) on the APC to CD28 on the T cell (UniProt: P33681, P42081). In clinical practice, this pathway is targeted to modulate immune responses; for example, Abatacept and Belatacept are fusion proteins that bind CD80 and CD86 to block co-stimulation, thereby treating autoimmune conditions like rheumatoid arthritis and preventing transplant rejection (StatPearls: NBK537012). Conversely, the pathway is also relevant in oncology, where checkpoint inhibitors target receptors like CTLA-4 that naturally compete with CD28 for these same ligands to prevent immune exhaustion. Monitoring the expression of these markers on APCs provides critical insights into the immune microenvironment and the efficacy of immunomodulatory therapies.

Other names

B7-1 (CD80)B7-2 (CD86)Major Histocompatibility Complex (MHC)Professional Antigen Presenting Cell markersHLA-DRB7 ligands

Competitive inhibition of CD28-mediated co-stimulation by binding to CD80 and CD86 ligands on antigen-presenting cells (StatPearls: NBK537012).