Effect of Polysaccharides and Human Plasma Lipoproteins on the Secretion of Cystatin C by Peritoneal Macrophages from Normal and Tumor Bearing Mice

Intact peritoneal macrophages in vitro secreted the cysteine proteinase inhibitor cystatin C. Polysaccharides stimulated cystatin C secretion: lipopolysaccharide < carboxymethylated beta-D-glucan < sulfoethylated beta-D-glucan. Human plasma low-density- (LDL) and high-density lipoproteins (HDL) are still more potent inducers of cystatin C secretion by macrophages. Peritoneal macrophages from mice with experimental HA-1 hepatoma compared to those from intact mice secreted more cystatin C with maximum polysaccharide-stimulated secretion after 30 min of incubation. LDL and HDL induced cystatin C secretion by tumor macrophages also.