Strain specific PD-1 and PD-L1 expression analysis in wild-type C57BL/6 and homozygous B-hPD-1/hPD-L1/hVEGFA mice by flow cytometry. Splenocytes were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hPD-1/hPD-L1/hVEGFA mice (H/H; H/H; H/H) after stimulated with or without anti-CD3ε in vivo. Mouse PD-1 and PD-L1 were detectable in wild-type C57BL/6 mice. Human PD-1 and PD-L1 were exclusively detectable in homozygous B-hPD-1/hPD-L1/hVEGFA mice but not in wild-type mice.

Strain specific VEGFA expression analysis in wild-type C57BL/6 mice and homozygous B-hPD-1/hPD-L1/hVEGFA mice by ELISA. Lung homogenates were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hPD-1/hPD-L1/hVEGFA mice (H/H; H/H; H/H). Mouse VEGFA was detectable in wild-type mice. Human VEGFA was exclusively detectable in homozygous B-hPD-1/hPD-L1/hVEGFA mice, but not in wild-type mice.

Frequency of leukocyte subpopulations in spleen by flow cytometry. Splenocytes were isolated from wild-type C57BL/6 mice and homozygous B-hPD-1/hPD-L1/hVEGFA mice (n=3, 10-week-old). A. Flow cytometry analysis of the splenocytes was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, dendritic cells, granulocytes, monocytes, macrophages, CD4+ T cells, CD8+ T cells and Tregs in B-hPD-1/hPD-L1/hVEGFA mice were similar to those in C57BL/6 mice, demonstrating that humanization of PD-1, PD-L1 and VEGFA does not change the frequency or distribution of these cell types in spleen. Values are expressed as mean ± SEM. Significance was determined by two-way ANOVA test.  *P < 0.05, **P < 0.01, ***p < 0.001.