Examination of the molecular diversity of α1 antitrypsin in urine: Deficit of an α1 globulin fraction on cellulose acetate membrane electrophoresis

Abstract

In the clinical field of nephrology, a non-invasive approach employing the analysis of electrophoretic patterns in urinary protein has been established. In this study a total of 52 urine samples with IgA nephropathy (IgAN), anti-neutrophil cytoplasmic antigen-associated crescentic glomerulonephritis (GN), and other types of GN were analyzed. Patients with high α1 globulin (α1G) fractions, which contained α1AT in cellulose acetate membrane electrophoresis (CAE), tended to have α1 antitrypsin (α1AT) of normal molecular weight (57 kDa and 49 kDa), while patients with a deficit α1G fraction tended to have α1AT of low molecular weight (<49 kDa) (P < 0.01). The α1G fraction was significantly higher in patients with IgAN, and there were significantly more patients with normal molecular weight α1AT compared to patients with other diseases (P < 0.01). The isoelectric point of α1AT with lower-weight molecules was more on the alkali side compared to higher-weight molecules in two-dimensional electrophoresis. Detecting changes in α1G fractions in CAE may support the differential diagnosis of IgAN from other types of GN. © 2005 Wiley-Liss, Inc.