Altered cytokine production in the elderly

Abstract

Elderly persons are more susceptible to bacterial and virus infections and neoplasias than young adults. This is related to an impaired immune response. Lymphocytes of the elderly show a decreased proliferation after induction with mitogens. The decreased proliferation is correlated to a decreased release of interleukin (IL)-2 and soluble IL-2 receptor (sIL-2R). However, IL-2R expression on the cell surface is normal. Interferon (IFN)-gamma as the main T-helper-1 (TH1) cytokine is produced less by lymphocytes of the elderly, whereas the TH2 cytokines IL-4 and IL-10 are produced in higher amounts as compared to stimulated lymphocytes of young donors. The decreased production of IFN-gamma is correlated to a decreased number of CD45RO+/CD8+ T cells. Therefore in the elderly there seems to be a dysregulation in the TH1/TH2-system which is predominated by TH2-functions. Monocyte function seems to be increased in the elderly. Leukocytes of elderly persons produce higher amounts of IL-1, IL-6, IL-8 and tumor necrosis factor (TNF)-alpha after induction with lipopolysaccharide (LPS) than leukocytes from young donors. In contrast, in vitro induction of IFN-alpha by viruses is decreased in the elderly compared to the young. In conclusion, there are cellular defects and dysfunctions in the elderly resulting in an altered immune response.