Anatomical loci of HIV-associated immune activation and association with viraemia

Summary Background Lymphocyte activation, associated with vaccination or infection, can be measured by positron emission tomography (PET). We investigated the ability of PET to detect and measure magnitude of lymph-node activation among asymptomatic HIV-1-infected individuals. Methods Initially we assessed PET response in eight HIV-1-uninfected individuals who had received licensed killed influenza vaccine. In an urban teaching hospital, we recruited 12 patients recently infected with HIV-1 ( Findings Node activation was more localised after vaccination than after HIV-1 infection. In early and chronic HIV-1 disease, node activation was greater in cervical and axillary than in inguinal and iliac chains (p r 2 =0·98, p Interpretation The anatomical restriction we noted may reflect microenvironmental niche selection, and tight correlation of PET signal with viraemia suggests target-cell activation determines steady-state viral replication.