Studies on glomerular immune solubilization by complement in patients with IgA nephropathy.

A study of the solubilization of glomerular immune deposits by serum or complement in patients with IgA nephropathy is described. Renal biopsy specimens were obtained from 15 patients with IgA nephropathy. These specimens were incubated with fresh and heated sera from healthy adults or with lyophilized complement components, i.e., C3 and C4, at 37 degrees C for one hour in plastic tubes. The sections were then stained with fluorescein isothiocyanate (FITC)-labelled anti-human IgA antisera and examined by fluorescence microscopy. Normal sera showed a marked capacity to solubilize the glomerular immune deposits characteristic of IgA nephropathy. The solubilization capacity was reduced after inactivation and absorption of sera with anti-human C3 antiserum. Lyophilized C3 or C4 did not show any ability to solubilize such deposits. It was concluded that the solubilization of glomerular immune deposits may require whole active (fresh) components of complement related to the alternative pathway.