The effect of aging on T-regulatory cell frequency in HIV infection.

T-regulatory cell (T-reg) frequency is increased in HIV infection and with aging. We evaluated the effect of age on total, memory and naïve T-reg percentages in untreated HIV infection. Older HIV(+) subjects had a total T-reg percent that is 2.8% (p=0.02) higher than among younger HIV(+), older HIV(-) and younger HIV(-) subjects. In HIV(+) subjects, the total T-reg percentage is inversely correlated with the lymphocyte proliferative responses to tetanus (r=-0.45, p=0.002) and Candida (r=-0.43, p=0.003) antigens. Similar correlations were seen between memory T-reg percentages and the lymphocyte proliferative response to tetanus and Candida in HIV(+) subjects. T-reg percentages did not correlate consistently with markers of immune activation. T-reg percentages are increased in the older HIV(+) population and may play a role in the accelerated disease progression seen in older HIV-infected persons.