Immunofluorescence is a useful technique in the study of human renal diseases, both from the point of view of elucidating pathogenic mechanisms and as a diagnostic tool.
The finding of characteristic staining patterns for immunoglobulins and complement indicates that many forms of glomerulonephritis are immune complex diseases and that a few are due to anti-GBM antibodies. On the other hand, in lipoid nephrosis and toxemia of pregnancy, deposits of immunoglobulins and complement are generally absent, indicating that immunologic mechanisms are probably not responsible for these glomerular diseases.
The finding of fibrin or other fibrinogen derivatives in glomeruli in toxemia of pregnancy and in certain forms of glomulonephritis supports the interpretation that these substances play a pathogenic role in certain glomerular diseases.
The use of immunofluorescence has led to the recognition of two previously unrecognized renal diseases: nephropathy with mesangial IgA-IgG deposits (Berger), and a tubular disorder with deposits of immunoglobulins and complement along the basement membrane.