Elevated plasma stromal cell-derived factor 1 protein level in the progression of HIV type I infection/AIDS

Stromal cell-derived factor 1 (SDF-1) is a unique chemokine involved in mul tiple organogenesis as well as in the regulation of HIV infection. Here we determined the plasma SDF-1 concentrations of 193 HIV-1-infected individual s and 154 normal Japanese volunteers by developing a highly sensitive measu rement system based on time-resolved fluoroimmunoassay (SDF-1 TR-FIA), This system is also valid for the mouse model to quantitate circulating SDF-1 c oncentration in vivo and thereby its correlation with CXCR4 expression leve l on CD4(+) T cells. Interestingly, plasma SDF-1 concentrations in HIV-1-in fected individuals were three times higher than those in a normal control g roup and plasma SDF-1 protein levels showed an inverse correlation with CD4 (+) T cell count and a positive correlation with plasma HIV-1 RNA load. Not ably, individuals with later stage HIV-1 infection, who maintained fewer th an 200 CD4(+) T cells per cubic milliliter and more than 10,000 copies of H IV-1 RNA per milliliter, showed the highest plasma SDF-1 level among indivi duals at any stage of HIV-1 infection, These results suggest that endogenou s SDF-1 is upregulated by HIV-1 infection, particularly in late-stage HIV-1 infection/AIDS.