Immune deposits in human glomerulopathy. Fluorescent microscopy findings in 366 kidney biopsies correlated to symptoms, clinical course and immunosuppressive therapy.

366 kidney biopsies from 339 patients, 290 of which were classified on combined light microscopy (LM) and clinical criteria as glomerulonephritis (GN) and 49 as non-glomerulonephritis nephropathy, were examined by immunofluorescent microscopy (IFM) without knowledge of the clinical or LM findings at the time of examination. The IFM findings in the glomeruli were correlated to (l) the LM diagnosis, (2) the clinical symptoms, (3) the clinical course, and (4) the effect of immunosuppressive treatment. A few IFM results were found to correlate significantly with the LM diagnosis and clinical symptoms, but not to the effect of immunosuppressive treatment. It was impossible using IFM alone to group patients into any specific categories with uniform symptomatology and prognosis. Defined by IFM "immune complex nephritis" was demonstrated in 72%, and linear nephritis was found in 2% of the patients with GN. IgA occurred more frequently in GN secondary to systemic disease, particularly in SLE (60%) and HSP (88%). IgA was demonstrated in only 10% of patients with nonglomerulonephritic nephropathy. Demonstration of IgA is therefore a good indicator for corroborating the LM diagnoses of GN. Demonstration of IgG and/or IgM in GN was not found to be sufficient evidence for GN because these deposits also appeared in 40% of patients with non-glomerulonephritic nephropathy. An immunopathological classification based solely on glomerular deposits of immunoglobulin/C3 appears to have no practical importance. The demonstration of glomerular deposits of immunoglobulin/C3, however, showed to be a necessary supplement to clinical and morphological findings in some instances, in order to attain practical diagnostic boundaries within the very ill-defined concept which today constitutes GN.