Increased expression of scavenger receptor type I gene in human peripheral blood from hyperlipidemic patients determined by quantitative additive RT-PCR

The scavenger receptors type I and II are mediators for the binding and uptake of chemically modified lipoproteins and are restricted to cells of monocyte origin. These receptors are highly expressed during the process of monocyte to macrophage differentiation. Quantitative mRNA levels of scavenger receptors from peripheral blood mononuclear cells have been analyzed in 29 hyperlipidemic patients and 15 healthy controls. Macrophage scavenger receptor isoforms transcripts were studied in circulating peripheral blood mononuclear cells with a modified RT-PCR method based on the use of a non-modified internal standard and a mathematical logistic adjustment of the standard curve. This method makes it feasible to study the variation in the expression of the scavenger receptors gene in peripheral blood during different physiopathological conditions. We studied the expression of the scavenger receptors gene in different blood cell lines and was present in only those of monocytic origin. The results have shown evidence that levels of scavenger receptor type I transcripts were proportional to apoB/cholesterol levels whereas type II receptors did not show any transcriptional variability. These findings suggest that the cholesterol level exerts a selective up-regulation of the scavenger receptor type I which is detectable by the induced increment of circulating monocytes in the blood of hyperlipidemic patients.