Abstract
Using a direct fluorescent staining technique, immunofluorescent microscopy (IFM) demonstrated glomerular deposits of Ig[immunoglobulin]G and IgM and/or fractions of complement [C] in kidney tissue from 24% of 33 patients examined post mortem and in 39% of kidney biopsies obtained from 23 patients on Li treatment. All the patients investigated had had normal blood pressure. There was no evidence of glomerulonephritis (GN) clinically, at light microscopy, or on laboratory investigation. These spontaneously deposited Ig and C fractions in glomeruli will obviously be demonstrated in kidney biopsies from patients with GN, even though they bear no relation to the disease. This will therefore preclude an immunopathological classification which relates to histological and clinical findings. A control study of the IFM findings in glomeruli on 13 surgically removed kidneys showed optimal identification and no further glomerular deposition of Ig during the 72 h following nephrectomy, at temperatures below 10.degree. C. Clq and C3 were less stable and were only demonstrated with certainty up to 24 h after nephrectomy.