A CD8 GENOMIC FRAGMENT THAT DIRECTS SUBSET-SPECIFIC EXPRESSION OF CD8IN TRANSGENIC MICE

Helper and cytotoxic T cell subsets require the expression of differen t coreceptors (CD4 and CD8, respectively) for their development and fu nction, We have cloned the CD8 gene locus from genomic cosmid and P1 l ibraries and analyzed the region around the CD8 alpha and CD8 beta gen es for gene expression regulatory elements, DNase I (DNase I) hypersen sitivity analysis of 80 kb in the CD8 locus identified four clusters o f putative regulatory regions, three of which are thymocyte specific, Transgenic mice carrying the cloned CDB alpha beta genomic locus and c ontaining the identified DNase I-hypersensitive site clusters express the transgenic CD8 in a developmentally regulated, tissue-specific, an d CD8 T cell subset-specific manner.