Determination of interleukin 2 receptor number of Con A stimulated human lymphocytes with aging

Defective proliferative responses of lymphocytes from elderly donors to various mitogens have been reported in numerous studies. The aim of the present work was to monitor the kinetic response of lymphocytes obtained from elderly and young individuals regarding the Con A stimulated proliferative response and IL-2 receptor expression. The studies were performed by flow cytometric analysis using FITC conjugated anti-IL-2 receptor monoclonal antibody. The data obtained show that beside a detectable decrease in the proliferative capacity of peripheral blood lymphocytes from elderly subjects, the mean IL-2 receptor number/cell did not decrease, but even slightly increased under ConA stimulation. The pattern of distribution of IL-2 receptor positive lymphocytes is different in young and elderly individuals. These data suggest that the decreased proliferative response observed with aging is not due to the decrease of IL-2 receptor number, but most probably to an altered post-receptorial signal transduction mechanism, coupled to changes in responsive cell populations.