CD86 is an 80 kD member of the immunoglobulin superfamily also known as B70 or B7-2. It is expressed on antigen presenting cells and activated T and B cells. CD86 is a ligand for CD28 and CD152 (CTLA-4). It is one of the accessory molecules that plays an important role in T cell-APC cell costimulatory interactions. The 24F antibody can block the co-stimulatory activity of CD86.