Isotypic and allotypic variation of human class II histocompatibility antigen α-chain genes

Abstract
DNA squences of 4 human class II histocompatibility antigen .alpha. chain DNA sequences (derived from cDNA [complementary DNA] and genomic clones representing DC1.alpha., DC4.alpha., DX.alpha. and SB.alpha.) are presented and compared to DR.alpha. and to mouse I-A.alpha. and I-E.alpha. sequences. The data suggest possible mechanisms for the generation of polymorphism and the evolution of the DR, DC and SB families.