Structure and evolution of the extended B7 family

Here, Joelle Henry and colleagues explore structural and evolutionary relat ionships between the B7 costimulator molecules and a growing number of mole cules encoded within the major. histocompatibility complex. They propose th at B7 and MHC genes are derived from it common ancestor, with several membe rs of this large gene family possibly having pivotal influences on T-cell a ctivation.