To date, despite the known benefits of antiretroviral therapy (ART), many HIV-infected people are presenting late with very low CD4+ T-cells levels below 350/ul. These patients are more likely to be diagnosed with opportunistic infections, their risk of death is higher and their rate of immunological improvement is slower (Mussini C et al., 2008). These patients often present a real challenge due to their advanced clinical status (Borghi V et al., 2008). Unfortunately, little is known about the clinical presentation of these patients, their responses to antiretroviral treatment and especially about the changes in the adaptive and innate immunity of the GALT.

The investigator proposes to evaluate the virological, immunological and clinical outcomes of ART in HIV-1 infected 'late presenters'. The investigator further wants to investigate the longitudinal dynamics of the innate and adaptive immunity restoration in the GALT and peripheral blood of HIV infected patients under ART. In particular the investigators want to longitudinally assess DCs, NK-cells, CD4+ T-cells und CD45RO+-T-cells as well as the levels of IFNγ, IFNα, TNFα, and IL-12 in the GALT and peripheral blood by flow cytometry and by real-time PCR and correlate these data with laboratory and clinical parameters.

The investigators expect that this longitudinal study and experiments outlined in the protocol will provide valuable information about several important issues of the clinical outcome of patients under ART as well as understanding immunopathology during HIV-infection.

Inclusion Criteria:

• Documented HIV infection
• Patients naive to antiretroviral treatment
• Age older than 18 years
• Indication for initiation of ART
• Informed consent

Exclusion Criteria:

• Patients on antiretroviral treatment
• No informed consent
• Estimated life expectancy <1 year
• Age <18 years

prospective longitudinal non- controlled phase IV study, 30 patients