PB B-cell counts and frequency of cases with monoclonal B cells in healthy subjects older than 40 years with normal lymphocyte counts, grouped according to age. (A) Frequency of PB monoclonal B cells in healthy subjects older than 40 years with normal lymphocyte counts, grouped according to age. Bars represent the percentage of cases within each age subgroup (from 40 to 97 years) displaying circulating B-cell clones. The numbers inside the picture represent the proportion of cases displaying circulating B-cell clones per decade: 40 to 49, 50 to 59, 60 to 69, 70 to 79, 80 to 89, and older than 90 years. (B) Peripheral blood absolute B-cell counts according to age of otherwise healthy adults without and with both CLL-like and non–CLL-like circulating clonal B cells.