To compare the impact of HIV infection and healthy ageing on monocyte phenotype and function and determine whether age-related changes induced by HIV are reversed in antiretroviral treated individuals.

A cross sectional study of monocyte ageing markers in viremic and virologically suppressed HIV-positive males aged 45 years or less and age-matched and elderly (≥65 years) HIV-uninfected individuals.

Age-related changes to monocyte phenotype and function were measured in whole blood assays ex vivo on both CD14(++)CD16(-) (CD14(+)) and CD14(variable)CD16(+) (CD16(+)) subsets. Plasma markers relevant to innate immune activation were measured by ELISA.

Monocytes from young viremic HIV-positive males resemble those from elderly controls, and show increased expression of CD11b (P < 0.0001 on CD14(+) and CD16(+)subsets) and decreased expression of CD62L and CD115 (P = 0.04 and 0.001, respectively, on CD14(+) monocytes) when compared with young uninfected controls. These changes were also present in young virologically suppressed HIV-positive males. Innate immune activation markers neopterin, soluble CD163 and CXCL10 were elevated in both young viremic (P < 0.0001 for all) and virologically suppressed (P = 0.0005, 0.003 and 0.002, respectively) HIV-positive males with levels in suppressed individuals resembling those observed in elderly controls. Like the elderly, CD14(+) monocytes from young HIV-positive males exhibited impaired phagocytic function (P = 0.007) and telomere-shortening (P = 0.03) as compared with young uninfected controls.

HIV infection induces changes to monocyte phenotype and function in young HIV-positive males that mimic those observed in elderly uninfected individuals, suggesting HIV may accelerate age-related changes to monocytes. Importantly, these defects persist in virologically suppressed HIV-positive individuals.