IL-10 in HIV infection: increasing serum IL-10 levels with disease progression - down-regulatory effect of potent anti-retroviral therapy

To examine the potential pathogenic role of IL-10 in HIV infection, we meas ured serum IL-10 levels in 51 HIV-infected patients and 23 healthy controls both on cross-sectional and longitudinal testing. All clinical groups (Cen ters for Disease Control (CDC) categories) of HIV-infected patients had sig nificantly higher circulating IL-10 levels than controls, with the highest levels among the AIDS patients, particularly in patients with ongoing Mycob acterium avium complex (MAC) infection. Among 32 HIV-infected patients foll owed with longitudinal testing (median observation time 39 months), patient s with disease progression had increasing IL-10 levels in serum, in contras t to non-progressing patients where levels were stable. While both IL-10 an d tumour necrosis factor-alpha (TNF-alpha) increased in patients with disea se progression, the IL-10/TNF-alpha ratio decreased in these patients, sugg esting imbalance between these two cytokines. Finally, we found that highly active anti-retroviral therapy (HAART) induced a significant, gradual decr ease in IL-10 levels but without normalization. These findings suggest a pa thogenic role for IL-10 in HIV infection, and may suggest a possible role f or immunomodulating therapy which down-regulates IL-10 activity in addition to concomitant potent anti-retroviral therapy in HIV-infected patients.