Background:

B-lymphocyte activation antigen B7-2, also known as CD86, is a member of the cell surface immunoglobulin superfamily. It is constitutively expressed on interdigitating dendritic cells, Langerhans cells, peripheral blood dendritic cells, memory B cells and germinal center B cells. Additionally, CD86 is expressed at low levels on monocytes and can be up-regulated through interferon γ. It exists predominantly as a monomer on cell surfaces and interacts with two co-stimulatory receptors CD28 and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) expressed on T cells (1). Subsequently, it induces the signal pathways which regulate T cell activation and tolerance, cytokine production and the generation of CTL (2). It has also been shown that CD86 promotes the generation of a mature APC repertoire as well as promoting APC function and survival. CD86 has an important role in chronic hemodialysis, allergic pulmonary inflammation, arthritis and antiviral responses, and thus is regarded as a promising candidate for immune therapy (3).