Longitudinal study of lymphocytes.

Longitudinal investigations of the peripheral lymphocytes of 91 healthy individuals were made over a period of six years. It was found that in aged subjects degenerative changes occurred in the mitochondria of the T cells. The number of subjects with damaged mitochondria in the lymphocytes increased significantly between 60 and 80 years of age. Six years after the first investigation, the number of individuals with damaged mitochondria also increased, with a peak between 70 and 79 years.