B- and T-lymphocyte Associated

Human CD272 (BTLA, B and T Lymphocyte Attenuator) is a member of the Immunoglobulin superfamily and has sequence homology to PD-1 and CTLA4. It is expressed on T and B lymphocytes and other hemopoetic lineages. Engagement of this molecule by its ligand, CD270 (HVEM, a TNF superfamily member) can down regulate activated T and B cell responses. CD272 levels on antigen specific CD8+ T cells have been reported to decrease in viral specific, but not melanoma specific activated lines (1). Polymorphism of the CD272 molecule has been linked to rheumatoid arthritis (3).