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

The basal production of IL-6 by cultured peripheral blood mononuclearcells (PBMC) from patients with IgAN, is markedly higher (A,109 pg/ml) as compared to that of PBMC of either patients withoutclinical signs (I, 39 pg/ml) or appropriate controls (C, 44pg/ml). When PBMC from healthy subjects were incubated in thepresence of sera from patients A, the IL-6 production was stronglyenhanced. No such an effect was observed by stimulating PBMCwith sera from the other two groups of subjects (I, C). In anotherexperiment we observed that the IL-6 production stimulated byserum from patients A could be inhibited by addition of specificmonosaccharides. The inhibitory effect was rapidly abolishedwhen the sugar-containing medium was substituted with the originalone. Finally molecular components from serum of A were grosslyseparated by gel column chromatography. Individual fractionswere incubated with PBMC of C: fractions with Mr > 30 000highly stimulated the release of IL-6 (up to 1320 pg/ml); fractionswith lower molecular weight were inactive. The data suggest the presence of an IL-6 releasing factor inthe serum of IgAN patients. Although the chemical nature ofsuch a factor is not yet established, the observations reportedfocus our attention to the lectins family. Since this factorseems potentially important in the understanding of the pathogenesisof IgAN, both its isolation and structural/functional characterizationdeserve further efforts.