FIG. 6.

HIV-induced C3 expression after the blocking of chemokine receptors in astrocytes. U373 astrocytes were incubated with either medium or HIV IIIB (20 ng of p24/ml). A part of the cells had been preincubated for 45 min at 4°C with neutralizing antibodies (10 μg/ml) against CCR5, CXCR4, or both, prior to addition of the virus. Control cells were either mock treated or incubated with the same amount of an unspecific IgG2a antibody. Secreted C3 was quantified after 6 days by ELISA. Results are the mean ± the standard deviation of duplicate determinations of a representative experiment. ∗∗∗, P < 0.005 versus the IgG2a control. OD, optical density.