T-lymphocyte activation antigen CD86 and T-cell-specific surface glycoprotein CD28 interaction (CD86–CD28 interaction)

The CD86–CD28 costimulatory interaction is a fundamental molecular bridge between antigen-presenting cells (APCs) and T lymphocytes, serving as the primary second signal required for full T-cell activation (UniProt P42081, P10747). CD86, a member of the B7 family, is constitutively expressed at low levels on APCs and rapidly upregulated upon activation, where it binds to the CD28 receptor on T cells to promote cell cycle progression, IL-2 production, and clonal expansion (PubMed: 10508230). In the absence of this interaction, T-cell receptor (TCR) signaling alone often results in functional unresponsiveness or anergy, making this pathway a key regulator of immune tolerance and activation. Dysregulation of the CD86–CD28 axis is implicated in the pathogenesis of numerous autoimmune diseases, such as rheumatoid arthritis and lupus, as well as in the acute and chronic rejection of solid organ transplants (StatPearls: NBK537012). Pharmacological intervention focuses on blocking this interaction to suppress unwanted immune responses; for example, Abatacept and Belatacept are recombinant fusion proteins that bind to CD86 to prevent its engagement with CD28 (PubMed: 23894002). These therapies have proven effective in reducing inflammation and improving graft survival, though they carry risks of immunosuppression-related infections and malignancies (FDA: Orencia Label).

Other names

B7-2–CD28 pathwayCD86–CD28 costimulatory pathwayB7.2–CD28 interactionCD86–CD28 axisB7:CD28 costimulation

Competitive inhibition of CD28 binding to CD86 by blocking the B7 ligand on antigen-presenting cells or the CD28 receptor on T cells, thereby preventing the costimulatory signal required for T-cell activation and proliferation.