Blood T‐Lymphocyte Functions in Healthy Adults in Relation to Age

Abstract

Blood T lymphocyte functions were studied in 167 healthy [human] adults (age range 19-91 yr). Lymphocyte DNA synthesis induced by concavalin A, pokeweed mitogen and PPD [purified protein derivative] antigen declined with age; the spontaneous DNA synthesis remained essentially unchanged. Relative and total T cell counts but not total lymphocyte counts were moderately decreased in elderly persons. The lymphocyte response to mitogens correlated with the PPD-induced activation in vitro. Lymphocyte and T cell counts did not show any association with the response to mitogens and antigen. A few subjects were tested on several occasions during 2-7 yr confirming a good reproducibility of the techniques employed. Thus, aging is associated with a diminished number of T cells and impairment of lymphocyte activation by T cell mitogens and PPD antigens. The clinical importance of this general age-related T cell deficiency remains largely unresolved.