Dr. Toshika Sakihama and colleagues in the Ellis Reinherz laboratory at Dana-Farber Cancer Institute made this human CD4 transgenic model on the murine Cd4 knockout background. A human CD4 molecule with a point mutation (Phe to Ile at amino acid residue 43) in the C’ strand residue of domain 1 (a region essential for binding MHC class II molecules) was generated by site-directed mutagenesis. The transgene was injected into fertilized eggs of mixed stock, and resultant transgene-positive mice were backcrossed to Cd4 knockout mice (Taconic model #1055) for 14 generations. The Cd4/hCD4 mice were received at Taconic in September 1999 and embryo transfer derived. The colony was maintained by breeding homozygous/hemizygous Cd4/hCD4 mice with homozygous Cd4 knockout mice to produce homozygous/hemizygous Cd4/hCD4 mice.
Sakihama T, Hunsicker ME, Hussey RE, Reinherz EL; Human CD4 residue Phe 43 is critical for repertoire development and maturation of MHC class II restricted CD4 single-positive T lineage cells in vivo; Eur J Immunol 2000 30:279-290. Note: The transgene with the point mutation (F43I) described in this publication is inserted on the X chromosome. The line received at Taconic has the same mutant hCD4, however, it is not linked to the X chromosome. The phenotype, class II MHC restriction and dependence are the same as described in the publication.