Memory B Cell Subpopulations in the Aged

The literature on immunosenescence has focused mainly on T cell impairment. With the aim of gaining insight into B cell immunosenescence, the authors investigated the serum IgD levels in 24 young and 21 old people and analyzed their relationship with the number of CD19 CD27 memory cells. Serum IgD were quantified by the use of radial immunodiffusion and the lymphocyte population CD19 CD27 was identified by a FACScan flow cytometer. Serum IgD levels were significantly lower (p 0.0001) in old subjects, and the percentage of CD19 CD27 lymphocytes were significantly increased (p 0.01) in old subjects. Finally, a significant negative correlation was found (p 0.01) between serum concentrations of…