FIG. 2.

C3 protein synthesis after incubation of U373 astrocytes with HIV IIIB. U373 astrocytes were either mock treated (−) or incubated with 50 ng of HIV IIIB/ml (+). Cell culture supernatants were harvested at different time points. (A) The amount of C3 protein was quantified by a specific ELISA. Results are the mean ± the standard deviation of triplicate determinations; the statistical significance of HIV-induced C3 production versus that of mock-treated cells was evaluated by Student's t test. ∗, P < 0.05; ∗∗, P < 0.01; ∗∗∗, P < 0.005; OD, optical density. (B) Supernatants were applied on a 9.5% acrylamide gel under reducing conditions, and Western blots were performed using a polyclonal C3-specific antibody. The arrow indicates the size of the C3 α-chain (113 kDa). Normal human serum (NHS) was applied on the gel as a positive control.