Inhibitory effects of human protein S on SR-A expression in human macrophages derived from THP-1 cells, U937 cells, and PBMCs. Macrophages were treated with protein S for 24 hours. (A) SR-A mRNA levels in THP-1 cells were analyzed by real-time PCR quantification. Results were normalized to the amount of GAPDH mRNA. (B) Protein levels of SR-A in THP-1 cells were detected by Western blot analysis. β-Actin was used as an internal control. (C) SR-A mRNA levels in U937 cells were analyzed by real-time PCR quantification. (D) Protein levels of SR-A in U937 cells were detected by Western blot analysis. (E) SR-A mRNA levels in PBMCs were analyzed by real-time PCR quantification. Representative results from 3 experiments are shown. Values are mean plus or minus SD of 3 experiments. *P < .05 versus untreated controls. SR-A indicates macrophage scavenger receptor A.