Investigations of the lymphokine system in elderly individuals

Elderly people are at risk from an increased incidence of infections. Therefore we have studied the correlation between the production of several immunological parameters such as interferon-gamma (IFN-gamma), interferon-alpha-2 (IFN-alpha-2), interleukin-2 (IL-2), soluble interleukin-2 receptors (sIL-2R) and interleukin-6 (IL-6) in young controls of 25-34 years old and old individuals with a minimum age of 65 years. All persons were selected according to the basic concept of the 'Senieur protocol'. Heparinized blood was taken and cultured in the whole-blood assay. The determination of all cytokines in the supernatants of stimulated cultures was done by the ELISA technique. We found significantly decreased levels of sIL-2R and IFN-alpha-2 after stimulation, whereas the values of IFN-gamma and IL-2 showed no significant difference between elderly and young persons. The values of IL-6 showed a distinct trend towards an increased synthesis for the elderly. We also studied the lymphocyte subpopulations T4 and T8 by flow cytometry. Elderly individuals showed a significantly increased T4/T8 ratio, caused by a slightly but not significantly decreased level of T8 cells. These results show that the elderly have decreased values of some immunological parameters such as IFN-alpha-2 and sIL-2R, which might explain an increased susceptibility of elderly individuals to bacterial and viral infections.