Strain specific CD4 expression analysis in heterozygous B-hCD4 mice by flow cytometry. Thymocytes were collected from wild type C57BL/6 (+/+) and heterozygous B-hCD4 mice (H/+) and analyzed by flow cytometry with species-specific anti-CD4 antibody. Mouse CD4 was detectable in WT mice and heterozygous B-hCD4 mice. Human CD4 was exclusively detectable in heterozygous B-hCD4 mice but not in WT mice.