Age-associated changes in interferon-gamma and interleukin-4 secretion by purified human CD4+and CD8+T cells

Aging is associated with a decline in immune function, Interferon-gamma (IF N-gamma) and interleukin-4 (IL-4), two important immune deviation-related c ytokines, are mainly produced by type 1 and type 2 T cells, respectively. T o investigate the age-associated changes in the secretion of these two cyto kines, 20 elderly and 20 young subjects fulfilling the SENIEUR protocol wer e enrolled. The ratios of CD4+ to CD8+ T cells were not different between t he two age groups, The CD4+ and CD8+ T cells were purified by a magnetic ce ll sorting system, and then activated by concurrent anti-CD3 a nd anti-CD28 stimulation, The released cytokines were determined by ELISA, Both the CD4 + and the CD8+ T cells of the elderly individuals secreted a significantly larger amount of IFN-gamma after activation. Profound IL-4 production by CD 8+ T cells was observed in the older subjects compared with that of the you ng subjects, These data suggested that age-associated decrease in immunity may be related to an imbalance in the secretion of immune deviation cytokin es, The number of IL-4-secreting CD8+ T cells (T cytotoxic 2) rose signific antly in the older individuals. Our design also provided a useful way to di fferentiate the T cell subsets secreting the same cytokine, such as IFN-gam ma-producing T helper 1 and T cytotoxic 1 cells. Copyright (C) 2000 Nationa l Science Council. ROC and S. Karger AG. Basel.