T cells from huCD3ε^HET and huCD3ε^HOM mice express OKT3 binding site.

(A) Amino acid alignment of corresponding human and mouse CD3e exons. Arrows indicate residues that have been shown to be necessary for OKT3 binding [17]. Mouse exon 5 was replaced with a humanized exon 5 (top line) to generate huCD3ε^HET or huCD3ε^HOM mice. (B) Representative flow cytometry plots of mouse splenocytes (gated on scatter profile, PI exclusion, and CD5) using antibodies specific for human (OKT3) or mouse (145-2C11) CD3ε, comparing WT, huCD3ε^HET, and huCD3ε^HOM mice. (C) Absolute T cell numbers across each genotype. n = 5–13, p<0.05. (D-F) Representative flow cytometry plots showing the frequency of CD4⁺ and CD8⁺ T cells (D), summarized frequencies (E), and absolute cell numbers (F) obtained from spleens of 6-8-week old mice from each genotype. Cells are gated on scatter profile and PI exclusion. (G) CD4:CD8 T cell number ratio from spleens. n = 13–15, *p<0.05.