SP-D-dependent regulation of NO metabolism in lipopolysaccharide-stimulated peritoneal macrophages.

This work was designed to study the role of surfactant protein D in the regulation of NO synthesis by "non-alveolar" microphages. We evaluated whether the effects of surfactant protein D depend on the phenotype of macrophages. In the absence of surfactant protein D, the LPS-induced iNOS response was shown to decrease in macrophages of native and proinflammatory phenotypes by 30%, and in macrophages of the antiinflammatory phenotype (by 63%). Under the influence of lipopolysaccharide in high doses (500 ng/ml), NO(2)*- production by mouse macrophages without surfactant protein D was reduced in native cells (by 25%), but increased in proinflammatory (by 40%) and antiinflammatory phenotypes (by 12% compared to mouse macrophages with surfactant protein D). Our results suggest that surfactant protein D is involved in the immune response in the whole organism, but not only in the lungs. The effect of surfactant protein D depends on the phenotype of macrophages.