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

CD80 and CD86 are closely related cell surface proteins belonging to the immunoglobulin superfamily. They are primarily expressed on antigen-presenting cells such as dendritic cells, activated B-cells, monocytes/macrophages, and can also be found on activated T-cells. Both molecules function as critical costimulatory ligands required for full activation of naïve T lymphocytes. They achieve this by binding to the receptors **CD28** and **CTLA4** on the surface of T-cells. Engagement with **CD28** provides a stimulatory signal that promotes T-cell proliferation and cytokine production; conversely, engagement with **CTLA4** delivers an inhibitory signal that dampens immune responses. Although structurally similar—each possessing extracellular Ig-like domains—CD80 has higher affinity but slower kinetics compared to CD86 in its interactions with these receptors. Both molecules play essential roles in initiating and maintaining adaptive immune responses; their expression is upregulated during infection or inflammation[1][2][3][4]. Therapeutic agents such as abatacept exploit this pathway by mimicking CTLA4 to block costimulation in autoimmune diseases or transplantation settings. Dysregulation or therapeutic targeting of these pathways can lead to altered immunity—either excessive suppression resulting in infection risk or insufficient control contributing to autoimmunity/cancer progression[2].

Other names

B7-1 (for CD80)B7-2 (for CD86)B7 familycostimulatory ligandsCluster of Differentiation 80/86

– Blockade of costimulatory signal to T cells by inhibiting interaction with CD28 or CTLA4 receptors on T cells, leading to reduced immune activation or tolerance induction[2][3][4].