Monoclonal B cells are frequent in the blood of otherwise healthy elderly people, and their frequency increases with age. (A) The graphic shows the percentage of all (both CD5⁺ and CD5^-) monoclonal B cells present in the blood of people older than 65 years, detected by an unbalanced κ/λ light chain ratio on the surface of blood B cells. Individuals are grouped according to age (65-74 years, and older than 75 years) and gender (white and black bars show the prevalence of B-cell clones among women and men, respectively). Numbers of female and male individuals with monoclonal populations within the total number of female and male individuals analyzed are shown. (B) The graphic shows the percentage of CD5⁺ classic CLL-like B-cell clones either detected by the unbalanced κ/λ light chain ratio or by a sequential gating strategy in the blood of people older than 65 years. Individuals are grouped according to age (65-74 years, and older than 75 years) and gender (white and black bars show the prevalence of B-cell clones among women and men, respectively). Numbers of female or male individuals with classic CLL-like clones within the total number of female and male individuals analyzed are shown.