CD86 type I membrane protein is a member of the immunoglobulin superfamily which is expressed by antigen-presenting cells, and acts as the ligand for two proteins at the cell surface of T cells, CD28 antigen and cytotoxic T-lymphocyte-associated protein 4. CD86 binding with CD28 protein is a co-stimulatory signal for initiation of the T-cell. CD86 binding with CTLA-4 negatively regulates T-cell activation and diminishes the immune response.