LAIR-1 is a glycoprotein(~32kDa) expressed on the surface of the majority of human peripheral blood mononuclear leukocytes including T cells , B cells, NK cells, macrophages and dendritic cells. LAIR-1 functions as an inhibitory receptor in NK cells, T cells and B cells. Lair-1 consists of a leader sequence, extracellular domain, transmembrane domain, cytoplasmic region. The extracellular domain of LAIR-1( 22-125aa) was overexpressed in E.coli, and purified by using conventional chromatography techniques.