title: Immunoglobulin light chains generate hydrogen peroxide.
abstract: As low molecular weight proteins, restriction from glomerular filtration is minimized, permitting significant amounts of Ig light chains to be endocytosed into the proximal tubule epithelium, particularly in plasma cell dyscrasias. Recent studies have shown that this effect of concentrating light chains within the proximal tubule alters cell function. This study demonstrated that light chains belonged to a class of proteins that are capable of catalyzing the formation of hydrogen peroxide. Sufficient amounts of hydrogen peroxide were produced in HK-2 cells to stimulate the production of monocyte chemoattractant protein-1 (MCP-1), a key chemokine involved in monocyte/macrophage migration and activation of the proximal tubule, and to increase lactate dehydrogenase release into the medium. The light chain-mediated effect on MCP-1 production was inhibited by co-incubation with 1,3-dimethyl-2-thiourea, which also inhibited lactate dehydrogenase release, and by pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB. The amount of light chain that stimulated an intracellular redox-signaling pathway in the proximal tubule cells was well within levels that are seen in patients who have plasma cell dyscrasias. The conclusion is that light chains possess a unique property that permits the development of intracellular oxidative stress that in turn promotes activation of the proximal tubule and elaboration of MCP-1.
authors.affiliation: Division of Nephrology/Department of Medicine, 642 Lyons-Harrison Research Building, 1530 Third Avenue, S., University of Alabama at Birmingham, Birmingham, AL 35294-0007, USA.
authors.forename: Pei-Xuan
authors.initials: PX
authors.lastname: Wang
authors.forename: Paul W
authors.initials: PW
authors.lastname: Sanders
mesh_terms: D002384:Catalysis; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007147:Immunoglobulin Light Chains / Q000494:pharmacology*; D007668:Kidney / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018384:Oxidative Stress; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D007147:Immunoglobulin Light Chains; C038983:1,3-dimethylthiourea; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D013890:Thiourea