Advance in the new inhibitory signal pathway of BTLA/HVEM

The B and T lymphocyte attenuator(BTLA),belonging to Ig supeffamily,is an inhibitory receptor discovered recently.Herpesvirus entry mediator(HVEM),the unique ligand of BTLA,was initially described as a member of TNFR family.Engagement of HVEM with LIGHT originated from the tumor-necrosis factor family transmits a positive signal.The interaction between BTLA and HVEM delivers co-inhibitory signal which results in downregulation of lymphocyte responses.The negative interregulation of these two receptors altered the traditional opinion on the inhibitory signal pathway.In this review,we discussed the biological activities of BTLA/HVEM,mechanism of signal transduction and the investigation on their relationship with the related diseases,in order to understand the regulation mechanism of immune responses and to provide new therapeutic strategies for cancer,allograft rejection and autoimmune diseases. Key words: BTLA; HVEM; Inhibitory receptor; Immune regulation