Correlation between circulating stromal cell-derived factor 1 levels and CD4(+) cell count in human immunodeficiency virus type 1-infected individuals

Stromal cell-derived factor 1 (SDF-1) is the natural ligand that recognizes CXCR4, which also serves as a coreceptor for some strains of HIV-1, In thi s study, we explored SDF-1 blood levels among HIV-1-infected individuals ex hibiting a wide range of CD4(+) cell counts, Plasma or serum concentrations of SDF-1 protein were measured by ELISA in samples from 31 HIV-1-seronegat ive individuals and 79 HIV-1-infected subjects, Although SDF-1 protein leve ls were stable for months among seronegative individuals (mean intrasubject variation, 17%), the absolute values varied widely (0.28 to 106.5 ng/ml; m ean, 25.6 ng/ml), In HIV-1-infected subjects, there was a direct correlatio n between SDF-1 level and CD4(+) cell count. Subjects with fewer than 50 CD 4(+) cells per cubic microliter of blood had significantly lower mean SDF-1 levels (+/-SD) than did either HIV-1-infected subjects with higher CD4(+) cell counts or uninfected controls: CD4(+) cell count <50, mean SDF-1 level of 10.7 +/- 33.7, 50 < CD4(+) cell count <200, mean SDF-1 level of 12.9 +/ - 19.0, 200 < CD4(+) cell count <500, mean SDF-1 level of 19.3 +/- 36.8; CD 4(+) cell count >500, mean SDF-1 level of 18.5 +/- 25.2; uninfected control mean SDF-1 level, 25.6 +/- 34.7. No significant change in SDF-1 level was detected after administration of antiretroviral therapy in nine subjects wi th advanced disease (mean intrasubject variation, 43%), Analysis of SDF-1 m RNA expression in lymph nodes from HIV-1-infected subjects at different dis ease stages revealed that the medullary cords contained stromal cells that express SDF-1 mRNA, This preliminary analysis suggests a possible link betw een lower SDF-1 levels and disease progression.