T-lymphocyte activation antigen CD80 and T-lymphocyte activation antigen CD86 (CD80/CD86)

T-lymphocyte activation antigens CD80 and CD86, also known as B7-1 and B7-2, are critical costimulatory molecules expressed on the surface of professional antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells [7, 14, 19]. They serve as the primary ligands for the CD28 and CTLA-4 receptors on T cells, playing a central role in the two-signal model of T-lymphocyte activation [1, 3, 12]. Binding of CD80/CD86 to CD28 provides the essential second signal for T-cell proliferation, cytokine production, and survival, whereas binding to CTLA-4 delivers inhibitory signals to maintain immune homeostasis [1, 7, 13]. In the context of organ transplantation and autoimmune diseases, the CD80/CD86-CD28 pathway is a major driver of immune-mediated tissue damage and graft rejection [3, 6, 8]. Drugs like belatacept and abatacept are CTLA-4-Ig fusion proteins that selectively bind to CD80 and CD86 with high affinity, effectively blocking their interaction with CD28 [1, 2, 30]. This blockade prevents full T-cell activation and induces a state of antigen-specific anergy or apoptosis, making these agents valuable for preventing kidney transplant rejection and treating rheumatoid arthritis [1, 3, 32]. However, therapeutic use requires careful monitoring for risks such as post-transplant lymphoproliferative disorder (PTLD) and opportunistic infections [1, 32, 39].

Other names

B7-1B7-2B7.1B7.2BB1B70CD28LG2LAB72

Belatacept and abatacept are CTLA-4-Ig fusion proteins that bind to CD80 and CD86 on antigen-presenting cells, competitively inhibiting their interaction with CD28 on T cells. This blockade prevents the costimulatory signal required for full T-cell activation, leading to T-cell anergy, apoptosis, and reduced production of inflammatory cytokines.