Fig. (1) gp120 inhibits SDF-1α induced chemotaxis of primary human resting CD4 T cells. (A) CD4 T cells were isolated and purified (98% pure) and pre-treated with either gp120 (IIIB) (1µg/ml) or BSA (1µg/ml) for indicated time to and then the percentage of CD4 T cells which underwent chemotaxis in response SDF-1α (40nM, 1 hour) was determined. P values were determined by Student’s paired t test. (B) Primary human unstimulated CD4 T cells were treated with gp120 IIIIB or BSA as described above, and expression of CXCR4 was measured by Flow Cytometry. The data is representative of three independent experiments.