ABSTRACT
<p><b>OBJECTIVE</b>Analyzing the relationships between peripheral blood CD4+ CD25hi regulatory T (Treg) cells and peripheral blood immune status or plasma HIV-lviral load in HIV-infected individuals,so as to determine whether Treg were related to the progression of HIV-infected disease.</p><p><b>METHODS</b>116 HIV-infected patients in different stages and 21 healthy control individuals were included in this study. The CD4+ and CD8+ T cell counts were determined by a standard 4-color flow cytometry technique. The Treg cells were examined with 3-color immune staining flow cytometry. The plasma HIV-1 viral load was detected by real time PCR.</p><p><b>RESULTS</b>The frequencies of Treg cells decreased in HIV-infected individuals with high CD4+ T cell counts( > 300/microl) compared with normal controls. With the progression of disease the frequencies of Treg cells were raised gradually, until were increased in HIV-infected individuals with low levels of CD4+ T cell counts ( < 100/microl). In addition, the frequencies of Treg cells were inversely related to CD4+ T cell counts and CD4+ /CD8+ ratio, data showed a statistically significant (respectively, r = -0.564, P < 0.001; r = -0.377, P < 0.001). Furthermore, the proportions of Treg cells were closely related to plasma HIV-1 RNA viral load (r = 0.514, P < 0.001).</p><p><b>CONCLUSION</b>CD4 CD25hi Treg cells should be a kind of important cells participating the immunopathogenesis of AIDS. It may play different roles in different stages of HIV-infected disease. The exact mechanism of Treg cells in the progression of the HIV-infected disease needs to be investigate further.</p>