Paraprotein-Related Kidney Disease: Attack of the Killer M Proteins.

Paraproteins are monoclonal Igs or their components (light or heavy chains) that are produced by a clonal population of mature B cells, most commonly plasma cells. These paraproteins or monoclonal proteins are secreted into the blood and subsequently filtered by the glomerulus before entering into urine, where they can cause various types of kidney disease, including both glomerular and tubulointerstitial injuries. Furthermore, a monoclonal protein that causes a specific glomerular or tubulointerstitial lesion in a human can reproducibly cause the same pathology when injected into an animal, supporting unique paraprotein characteristics. This Moving Points in Nephrology will provide an update for the Clinical Journal of the American Society of Nephrology readership on some of the clinically relevant kidney lesions associated with monoclonal paraprotein production and the pathophysiology underlying these kidney lesions.