免疫球蛋白(Ig)经木瓜酶水解后的结晶片段(Fragment Crystalline),具有固定补体,结合细胞等生物学功能,称Fc片段。现发现T、B淋巴细胞、巨噬细胞、K细胞、NK细胞、粒细胞、肥大细胞和血小板等细胞表面都有Fc受体(Fcreceptor、FcR)。FcR能对与性同Ig分子的重链未端Fc部分结合。FcR与游离状态的lg结合力弱,且易解离, Immunoglobulin (Ig) Fragment Crystalline hydrolyzed by papain, with fixed complement, binding cells and other biological functions, called Fc fragment. It has been found that T, B lymphocytes, macrophages, K cells, NK cells, granulocytes, mast cells and platelet cells have Fc receptor (Fcreceptor, FcR). FcR binds to the heavy chain, non-terminal Fc portion of sex-identical Ig molecules. FcR and free state lg weak binding, and easy to dissociate,