Normal T-cell development and decreased numbers of MZB cells in Maml1^+/− mice. (A) Flow cytometric analysis showed a similar percentage of CD4⁺CD8⁺ double-positive and CD4⁺ or CD8⁺ single-positive cells in the thymus of Maml1^+/− mice compared with wild-type littermates. Numbers indicate the percentage of cells in each quadrant. (B) Flow cytometric analysis of splenic B-cell subsets showing a reduced percentage of B220⁺CD21^hiCD23^lo MZB cells in Maml1^+/− compared with wild-type spleens. Numbers indicate the percentage of cells in the rectangular box identifying MZB cells. (C) Data from multiple mice were compiled, indicating significant Maml1 dosage-dependent decrease in MZB cells. Each triangle represents a data point for a single mouse (Maml1^+/+, ▴, n = 5; Maml1^+/−, ▵, n = 5).