Strain specific PD-L1 expression analysis in wild-type BALB/c mice and heterozygous B-hPD-L1 mice(C) by flow cytometry. Splenocytes were collected from wild-type BALB/c mice and heterozygous B-hPD-L1 mice(C) stimulated with anti-CD3ε in vivo (7.5 μg/mice, stimulation for 24 hours, i.p.). Mouse PD-L1 was both detectable in wild-type mice and heterozygous B-hPD-L1 mice(C). Human PD-L1 was only detectable in heterozygous B-hPD-L1 mice(C).