Analysis of an expanded width of albumin fraction by cellulose acetate membrane electrophoresis in IgA nephropathy urine before treatment

Cellulose acetate membrane electrophoresis with colloidal silver stain re-vealed that the width of the albumin fraction in IgA nephropathy (IgAN) urine before treatment was significantly expanded. This phenomenon was not shown in IgAN urine after treatment or in non-IgAN urine. There was a reverse correlation between the width of the albumin fraction and the albumin con-centration in IgAN urine. By immuno-fixation, Tamm-Horsfall protein (THP) was located in the same position as the albumin band in IgAN urine before treatment; however, in the urine of a healthy subject it was located in the same position as alpha(1)-globulin. By ELISA, the THP-albumin complex concentration in IgAN urine before treatment was significantly higher than in the other two diseases. The width of the albumin fraction and the sodium ion concentra-tion of the urine were significantly correlated. The THP/albumin ratio in IgAN urine before treatment was significantly higher than in the other two groups. This suggests that the characteristic expanded width of albumin found by immunofixation indicates a THP-albumin complex, and that the sodium concentration of urine is involved in the formation of this complex.