Analysis of B-cell maturity in hu-mice. (A) Representative flow cytometric analysis of immature and mature B cells and of T cells in the spleen of BRGS (top) and hBAFFKI-BRGS (bottom) hu-mice. Plasmablasts (PB), identified as CD38 very-high (CD38^vhigh) and CD10⁻, were gated by Boolean gate on CD20⁺ (and hCD45⁺) cells to remove them from the rest of the analysis (left column). Remaining CD20⁺ cells (-PB) were analyzed for CD10, CD24, and CD38 (second and third columns) to establish the proportion of immature/transitional (imm./tr.; CD10⁺ and CD24^highCD38^high) and mature (CD24^lowCD38^low) or mature/memory (mat./mem.; CD10⁻) B cells. hCD45⁺ cells were analyzed to establish frequencies of CD3⁺ T cells (right column). (B) Frequencies of mature B cells (CD10⁻, left; CD24^lowCD38^low, right) within the CD20⁺ (-PB) spleen B-cell fraction of individual BRGS (□) and hBAFFKI-BRGS (▪) hu-mice. (C) Absolute numbers of immature (CD24^highCD38^high) B cells (left) and of mature (CD24^lowCD38^low) B cells (right). (D) Correlation between immature (CD24^highCD38^high) and mature (CD24^lowCD38^low) B-cell numbers in the spleen of each hu-mouse. Statistical differences were analyzed by paired Student t test. (E) Scatter plot analysis of the percentage of CD10⁻ mature/memory B cells within the CD20⁺ (-PB) cell population (y-axis) relative to the frequency of CD3⁺ T cells within the hCD45⁺ cell population (x-axis) in the spleen of each hu-mouse. Linear regression analyses are shown separately for BRGS and hBAFFKI-BRGS groups of hu-mice. (F) Frequencies of CD3⁺ T cells in the hCD45⁺ spleen cell population (left) and absolute cell numbers (right) in BRGS and hBAFFKI-BRGS hu-mice. (G) Frequencies of T cells (left) and of mature B cells (right) in a subset of BRGS and hBAFFKI-BRGS hu-mice with comparable proportion of T cells (>30% and <54% within hCD45⁺). Each symbol in panels B through G represents a mouse; bars are mean and SEM. N = 16 to 21 mice per group (in B-G) and 4 different CB groups. *P < .05; ***P < .001.