CD86 is among the two ligands (the other being CD80) to activate CTLA4 as well as CD28. CD86 is an inhibitory molecule that triggers T-cell support in the course of antigen presentation. Antigen presentation that is devoid of adequate co-stimulation with CD86/CD80 may induce tolerance. CD80 seems to play a different role from CD80 in the differentiation of T helper cells.
CD86 is a membrane-bound type I protein, which is part of the superfamily immunoglobulin. The CD86 antibody protein is expressed by antigen-presenting cells, and it is the ligand for two proteins at the cell surface of T cells, CD28 antigen and cytotoxic T-lymphocyte-associated protein 4. The binding to CD86 to CD28 antigen can be a signal to activate the T-cell.
Binding of CD86 with cytotoxic T-lymphocyte-associated protein 4 negatively regulates T-cell activation and diminishes the immune response. Alternate splicing results in two transcript variants that encode various isoforms of CD86. Other transcript variants have been identified for CD86 however their full sequences aren't known. Conditions that can be attributed to CD86 impairment include gallbladder squamous-cell carcinoma and myocarditis.
CD80, as well as CD86 (B7-2 B70), are part of the B7 family, cell surface ligands that regulate the activation of T cells and immune responses. CD80 can be found on activated antigen-presenting cells, which include dendritic cell B cells, monocytes and macrophages. CD86 can be found on monocytes that are resting and dendritic cells, activate B lymphocytes and can be increased in the event of an inflammation.