Characteristics of human CD19⁺cells recovered from blood, BM, and spleen of RG SKI and RG SKI IL-6 mice. (A) Gates used for identification of human naïve, memory, transitional/immature, or plasmablast B cells by flow cytometry based on the expression of hCD27, hCD10 hIgD, hCD24, and hCD38. Plasmablasts also have large cell size measured by forward scatter (FSC)/side scatter (SSC). (B) Relative abundance of each B-cell subset compared between two mouse strains at different time points. Two independent experiments were performed and the results were pooled. Data represent the mean ± SEM (n = 12-15 per group) and were analyzed by two-way ANOVA, Tukey’s multiple comparisons test.