Cpa3^tm3(icre)Hrr

The coding sequence for the first 28 nucleotides of the gene locus was replaced with a codon-improved cre recombinase expression cassette and a Frt-flanked neomycin selection cassette. Transient expression of Flp-recombinase in correctly targeted ES cells removed the selection cassette. When mice carrying this cre knock-in allele were crossed with mice carrying the cre-dependent reporter allele Gt(ROSA)26Sortm1Hjf, reporter expression was observed in about 25% of early pro-T cells in the thymus. By the DN2 stage (CD44+CD25+CD4-CD8-) of T cell development, 90% of the cells expressed the reporter as did 90% of peripheral T cells. A small percentage (<5%) of mature B cells also expressed the reporter. Bone marrow analysis demonstrated expression in some (10-30%) stem cells, common lymphoid progenitors and in myeloid- and plasmacytoid- dendritic cells. (J:143731, J:178942)