Regulatory effects of LBP on the expressions of TNFα and IL-10 mRNA induced by LPS in alveolar macrophages of rats

Objective To investigate the regulatory effects of lipopolysaccharide binding protein(LBP) on expressions of TNFα and IL-10 mRNA induced by lipopolysaccharide (LPS) in alveolar macrophages. Methods LBP was purified from serum of rat in acute phase by precipitating with ammonium sulphate and passed through Bio-Rex 70 resin and MonoQ column. Rat alveolar macrophages were exposed to LPS(10 ng/ml or 1 000 ng/ml) in different concentrations of LBP. Total RNA was extracted for assay of TNFα and IL-10 mRNA expressions by RT-PCR. Results The puri- fied preparation of rat LBP showed a homogeneity with a molecular weigh of 60 x 103 in SDS-PAGE analysis. The binding of lipopolysaccharide to mononuclear cells was enhanced by purified rat LBP. Stimulation of ral alveolar macrophages with LPS at the concentration of 10 ng/ml was LBP de- pendent. LBP of concentrations up to 1 μg/ml was able to increase TNFα and IL-10 mRNA expressions both TNFα and IL-10 mRNA level were lower at 10 μg/ml as compared with that in the presence of 1 μg/ml. Stimulation of rat alveolar macrophages with LPS at concentrations of 1 000 ng/ml was LBP independent. Conclusion The regulatory effects of LBP on LPS is dose dependent and the macrophages could be directly activated by LPS at higher concentration.