Low DNA damage in peripheral lymphocytes of healthy elderly individuals with inverted CD4:CD8 ratio

Abstract

The aim of this study was to evaluate the DNA damage in peripheral lymphocytes and the frequencies of CD8+ T cells expressing CD25, CD28 and CD45ro in aged individuals with inverted CD4:CD8 ratio. Blood samples of elderly individuals (aged >65) with normal CD4:CD8 ratio (n = 8) and inverted CD4:CD8 ratio (n = 8) were collected to identify the expression of CD25+, CD28+ and CD45ro+ in CD8+ T cells. DNA damage index was evaluated by the alkaline comet assay which was performed in lymphocytes treated with different concentrations of methyl methanesulfonate (MMS) (control non-treatment, 2 × 10−5 M, 4 × 10−5 M) for 1, 2 or 24 h. Elderly individuals with inverted CD4:CD8 ratio presented low frequency of CD8+ CD28+. Moreover, low DNA damage was observed in lymphocytes of elderly with inverted CD4:CD8 ratio in different doses of MMS. Aged individuals with inverted CD4:CD8 ratio presented lower DNA damage events in peripheral lymphocytes, suggesting a resistance for cell death in T cells of individuals with immune risk profile.