The defect of IgM⁺IgD⁺CD27⁺ cells is stable with age. Ratio of the IgD⁺CD27⁺ versus IgD⁻CD27⁺ cell proportions as a function of age in control patients (A) and in several patients deficient for IRAK-4 who were analyzed at different ages (B). Control patients are divided into 3 different age groups.