Interleukin-6 production induced in peripheral blood mononuclear cells by a serum factor from IgA nephropathy patients is inhibited in vitro by specific sugars

Abstract

The basal production of IL-6 by cultured peripheral blood mononuclear cells (PBMC) from patients with IgAN, is markedly higher (A, 109 pg/ml) as compared to that of PBMC of either patients without clinical signs (I, 39 pg/ml) or appropriate controls (C, 44 pg/ml). When PBMC from healthy subjects were incubated in the presence of sera from patients A, the IL-6 production was strongly enhanced. No such an effect was observed by stimulating PBMC with sera from the other two groups of subjects (I, C). In another experiment we observed that the IL-6 production stimulated by serum from patients A could be inhibited by addition of specific monosaccharides. The inhibitory effect was rapidly abolished when the sugar-containing medium was substituted with the original one. Finally molecular components from serum of A were grossly separated by gel column chromatography. Individual fractions were incubated with PBMC of C: fractions with Mr > 30,000 highly stimulated the release of IL-6 (up to 1320 pg/ml); fractions with lower molecular weight were inactive. The data suggest the presence of an IL-6 releasing factor in the serum of IgAN patients. Although the chemical nature of such a factor is not yet established, the observations reported focus our attention to the lectins family. Since this factor seems potentially important in the understanding of the pathogenesis of IgAN, both its isolation and structural/functional characterization deserve further efforts.