CD86 also known as B7-2 is a protein expressed on antigen-presenting cells that provides costimulatory signals necessary for T cell activation and survival.

The CD86 gene encodes a type I membrane protein that is a member of the immunoglobulin superfamily. Using fluorescence in situ hybridisation mapping, the CD86, like CD80, was mapped to human 3q21 and mouse chromosome 16, band B5.

The antigen presentation coactivator B72 is important in other immune-mediated thyroid diseases, lymphocytic infiltration and the immune response against thyroid carcinoma.