Urine proteins in renal disease. II. Alpha 2-microgiobulins in tubular proteinurias with special reference to endemic nephropathy.

Urine microglobulins were analyzed in 145 patients with a variety of chronic renal disease, 58 of whom had endemic nephropathy. On agarose-gel electrophoresis, the urinary-protein patterns of either tubular or mixed tubulo-glomerular type invariably showed two to three discrete alpha 2-migrating bands differing slightly in net charge. Marked differences in their relative concentrations occurred from one case to another and, following prolonged storage at 4 degrees C, in the same urine as well. All three fractions showed only a single precipitation line on immunoelectrophoresis when tested against antisera to urinary proteins; thus it would appear that they represent differently charged, but antigenically identical molecular forms of a protein of low molecular weight. The results also suggest that their detection might be used as an indicator for clinical purpose of impaired tubular function.