在第6号染色体上连锁排列的基因群-人类主要组织相容性复合体(MHC)在免疫应答的多个阶段中起着重要的作用。它至少控制着三类分子,每一类都以不同的方式介导对外源性抗原的应答。传统的移植抗原HLA-A,-B和-C为I类分子,HLA-D区抗原为Ⅱ类分子。它们都具有高的度多态性。MHCⅢ类分子-补体成分C_2、C_4和 Gene clusters linked on chromosome 6, the human major histocompatibility complex (MHC), play an important role in multiple stages of an immune response. It controls at least three classes of molecules, each of which mediates the response to foreign antigens in a different way. Conventional transplant antigens HLA-A, -B and -C are class I molecules and HLA-D region antigens are class II molecules. They all have high degree of polymorphism. MHC class III molecules - complement components C_2, C_4 and