Gene targeting strategy for B-hCD45 mice. The extracellular region of mouse Cd45 gene was replaced by the counterpart gene sequences of human CD45 in B-hCD45 mice.

Strain specific CD45 expression analysis in heterozygous B-hCD45 mice by flow cytometry. Blood was collected from wild-type C57BL/6 (+/+) and heterozygous B-hCD45 mice (H/+) and analyzed by flow cytometry with species-specific anti-CD45 antibody. Mouse CD45 was detectable in wild-type mice and heterozygous B-hCD45 mice. Human CD45 was exclusively detectable in heterozygous B-hCD45 mice but not in wild-type mice.