Distinct regulatory elements are required for faithful expression of humanCD4 in T cells, macrophages, and dendritic cells of transgenic mice

To Identify the regulatory elements controlling expression of the human CD4 (hCD4) gene in different cell types of the immune system, deletion and chi meric (human/murine) reporter genes were constructed and tested In transgen ic (Tg) mice. Regulatory elements required for the proper hCD4 expression I n the immature double-positive thymic T cells were identified in the enhanc er and in the 3 ' end of intron 1. Expression of hCD4 in macrophages is con trolled by at least 2 sets of regulatory elements: one present in front of exon 1 and the second at the 5 ' end of Intron 1. The hCD4 elements require d for expression on both myeloid and lymphoid CD8 alpha (+) dendritic cells (DCs) from lymph node and thymus were found to be different from those req uired for macrophage expression. The results indicate that expression of hC D4 in T cells, macrophages, and DCs is controlled by distinct regulatory el ements. (C) 2001 by The American Society of Hematology.