Strain specific FCER1A expression analysis in homozygous B-hFCER1A mice by flow cytometry. Basophilic granulocytes of the blood were collected from wild type (WT) mice (+/+) and homozygous B-hFCER1A mice (H/H), and analyzed by flow cytometry with species-specific anti-FCER1A antibody. Mouse FCER1A was detectable in WT mice (+/+). Human FCER1A was exclusively detectable in homozygous B-hFCER1A mice (H/H) but not in WT mice (+/+).