Development and diversification of IgM⁺IgD⁺CD27⁺ peripheral B cells from healthy and asplenic children. (A) (B) (C) (D) Percentage of IgM⁺IgD⁺CD27⁺ peripheral B cells from healthy (A) and asplenic children (C) younger than 5 years. Mutation frequency of rearranged V3-23 genes from IgM⁺IgD⁺CD27⁺ peripheral B cells of healthy (B) and asplenic children (D). In panels B and D, each bar represents the mutation frequency of one individual, and the values marked above the bars represent the mutation range over the 288 bp V3-23 sequence analyzed; healthy adult values are pooled from 5 individuals. (E) IgD/CD27 staining profiles of peripheral CD19⁺ lymphocytes of asplenic individuals from 14 months to 71 years. The percentage of cells in each CD27⁺ quadrant is indicated. A complete description of asplenic patients is given in Table 3.