Cell-Mediated Immunity (CMI) and bactericidal function in apparently healthy, well-nourished elderly vs younger women

As part of an ongoing study on iron status and immune function, to collect baseline data and determine effects of aging on immunocompetence we examined CMI and bactericidal function in a cohort of older (O, n=12, age: 65-85y) versus younger (Y, n=21, age: 20-40y) women. Subjects were apparently healthy, free from inflammation, and generally well-nourished based on clinical chemistry and hematological tests. Our preliminary results suggest that although % lymphocytes in both age groups was normal, it was 23% higher in O vs Y (p<0.05). Specifically, total T- (CDS⁺) and T-helper (CD4⁺) subsets were higher (27 and 30% respectively) in O vs Y (p<0.05). The proliferation response of T cells to stimulation with phytohemagglutinin (PHA) was 55% lower in O vs Y (p<0.05), while no difference was seen with Concanavalin A. Natural killer (NK) cell activity expressed as % specific target cell lysis per NK cell was 41% lower in older women (p<0.05). The oxidative burst capacity of granulocytes and monocytes was unaffected with age (p>0.05). Based on our preliminary examination, we conclude that immunosenescence was limited to certain cell function markers (T-cell proliferation response to PHA, and NK cell activity) while other immune parameters were not compromised with age.