INTRACELLULAR CU ZN SUPEROXIDE-DISMUTASE LEVELS IN T-CELLS AND NON-T-CELLS FROM NORMAL AGED SUBJECTS/

The decreased immune response associated with aging may, in part, refl ect intrinsic age-related biochemical alteration in lymphocytes from o lder subjects. The reactive oxygen species hypothesis' of aging postul ates that these molecules are involved in the modifications leading to cellular senescence. Superoxide dismutase (SOD), and in particular th e Cu/Zn-dependent intracellular form, plays a critical role in the def ense against these species, but it is controversial whether this funct ion declines in lymphocytes in old age. We utilized two different meth ods to evaluate Cu/Zn SOD levels in T and non-T cells (CD3(+). CD3(-). CD4(+) CD8(+), CD16(+)) from young and old individuals: a specific an d sensitive enzyme immunoassay performed on extracts of sorted cells, and a flow cytometry double Fluorescence technique with monoclonal ant ibodies against Cu/Zn SOD and the different lymphocyte subsets. The Cu /Zn SOD cell content was assayed both in basal conditions and after pe ripheral blood lymphocyte stimulation with Concanavalin A, anti-CD3 mo noclonal antibody and phorbol myristate acetate. In basal conditions, and considering the various subsets, no differences were found between young and old individuals, although data analysis revealed high and l ow responders in both groups. Taking all the subjects together, higher levels of this enzyme were found in CD3(+) T lymphocytes, in particul ar in the CD4(+) cells. After peripheral blood lymphocyte stimulation, Cu/Zn SOD concentration was higher than levels in unstimulated cells, both in young and old individuals, and particularly using Concanavali n A with respect to anti-CD3 and phorbol myristate acetate. In conclus ion, the synthesis of Cu/Zn SOD does not seem to be affected by aging in proliferating cells. The highest levels of Cu/Zn SOD present in CD4 (+) cells, both from young and old individuals, may prevent the oxidan t stress of these elements which play a major role in the inflammation sites.