Comparison of CD27 expression between immune cell populations of humans and humanized mice. (A) Humanized mice (huMice) reconstitution scheme. Immunodeficient NOD mice with a loss-of-function mutation in the Prkdc gene and common γ chain deficiency (NOD-scid γ_c^null, or NSG) were engrafted with human CD34⁺ HPCs to reconstitute human immune system components and were tested for human immune compartment reconstitution after 3 months. (B) Pie charts show the distribution of CD27⁺ cells in different immune cell populations examined in huMice blood (n = 3) and human PBMCs (n = 3). (C) Frequency of CD27⁺ cells in different immune cell populations, comparing huMice peripheral blood (n = 3) and human PBMCs (n = 3). NK, natural killer. (D-E) Representative flow cytometry analysis illustrating the gating strategy to differentiate memory T-cell subsets characterized by CCR7 and CD45RA expression within the CD3⁺CD27⁺ population (D) and the frequency of each subset (E), comparing huMice peripheral blood (n = 3) and human PBMCs (n = 3). See also related supplemental Figure 1.