The last advances of study on the new co-inhibitory molecule-BTLA

B and T lymphocyte attenuator(BTLA)is a new member of Immunoglobulin family which had been found recentlv.As inhibiting receptor which negatively regulates immune responses as cytotoxic T lymphocyte related antigen 4(CTLA-4)and Programmed death 1(PD-1),BTLA mainly expressed on the T and B lymphocyte.After binding to its ligand,BTLA can inhibit the proliferation of activated T cells,thus maintain the immunologic tolerance and keep the immunologic balance of the host.However,the real ligand of BTLA,as well as the mechanism of the BTLA signal pathway,has not been clear yet.Therefore,the lastest findings of structure,the ligand and the role of BTLA in the process of immune responses were described in this review. Key words: B and T lymphocyte attenuator; Inhibitory signaling; T lymphocyte; Immunity