Figure 1. B lymphocyte cell numbers in immune tissues. B220⁺CD19⁺ B lymphocytes were quantified via flow cytometry. Peritoneal B cell subsets were defined as follows: B-1a (B220^low, IgD^low, IgM⁺ and CD5⁺), B-1b (B220^low, IgD^low, IgM⁺ and CD5^-) and B-2 (B220^high, IgD⁺, IgM⁺ and CD5^-). Significance was determined using Student’s t test. *p < 0.001 compared with WT; n = 20 per group.