Changes in circulating immune complex and charge distribution with upper respiratory tract inflammation in IgA nephropathy.

The circulating IgA class immune complex (IgA-IC) and its charge distribution, at the appearance of macroscopic hematuria and after tonsillectomy in patients with IgA nephropathy, were investigated in the present study. 3.5% polyethylene glycol precipitate (3.5% PEG-IgA) was used for IgA-IC detection and isoelectric focusing for its charge distribution. The level of IgA in 3.5% PEG-IgA, principally IgA1, and the proportion of anionic 3.5% PEG-IgA (isoelectric point, pl, 4.8-5.6) were significantly elevated in episodes of macroscopic hematuria with upper respiratory tract inflammation and with the appearance of macroscopic hematuria 1 day after tonsillectomy. Therefore, an increase in anionic IgA-IC (pl 4.8-5.6), principally IgA1, and the tonsils were considered to be concerned with the mechanism involved in the appearance of macroscopic hematuria.