Abstract
We used Western blotting to investigate the structure of IgG in normal and pathologic urine that had been stored for 4 days under a range of conditions of pH and temperature. Urinary IgG in normal and pathologic urine was generally stable independently of storage conditions. Although intact IgG was the predominant form, IgG was varied in structure, and small fractions and Fcγ fragments appeared by the forth day. IgG and, to a lesser degree, its fragments, especially Fcγ fragments, were identified in normal and pathologic serum in patients with chronic renal failure, showing that these fragments are derived from both the serum and the urine. The latex agglutination photometric assay showed urinary IgG values to be constant, even when it detected minor components of IgG fragments as well as intact IgG. This structural stability makes urinary IgG acceptable as a maker for a glomerular dysfunction.
