B7-1 (CD80) and B7-2 (CD86) (CD80 (for B7-1), CD86 (for B7-2))

B7-1 (CD80) and B7-2 (CD86) are homologous cell-surface costimulatory ligands expressed on antigen-presenting cells. They belong to the immunoglobulin superfamily, each comprising extracellular IgV and IgC domains. Both B7-1 and B7-2 interact with the CD28 and CTLA-4 receptors on T cells, serving as critical regulators of T cell activation, tolerance, and immune response. B7-1 tends to be inducibly expressed and commonly exists as a dimer, while B7-2 is constitutively present and is usually monomeric on the cell surface[1][4][5][8]. Although they perform similar functions, their distinct oligomeric states, binding affinities, and temporal expression confer nuanced differences in immune modulation. The B7-1/B7-2 pathways are therapeutically targeted in cancer treatment and organ transplantation to regulate immune responses[6][8]. Modulating these interactions with drugs such as abatacept or belatacept can prevent inappropriate T cell activation or tolerance, but these therapies carry immunological safety concerns including higher infection risk and potential for unwanted alteration of immune homeostasis.

Other names

B7-1 (CD80)B7-2 (CD86)Cluster of differentiation 80Cluster of differentiation 86B7 family costimulatory moleculeB7 costimulatory molecule

Blockade of B7-1/B7-2 interaction with CD28 inhibits T cell activation. Blockade of B7-1/B7-2 interaction with CTLA-4 prevents inhibitory signaling, enhancing immune activation. Fusion proteins (e.g., abatacept, belatacept) act as decoy receptors, binding B7-1/B7-2 and preventing costimulatory signaling to T cells