Immunofluorescent Localization of Antihemophilic Factor Antigen and Fibrinogen in Human Renal Diseases

factor (AHF, factor VIII) antigen and fibrinogen by immunofluorescent microscopy was determined in 146 specimens of normal and diseased kidneys. AHF antigen was present in the endothelial cells of glomeruli, peri-tubular capillaries, arteries, and veins of normal kid-neys; a distribution similar to that in other tissues. In scleroderma and malignant hypertension, deposition of AHF antigen and fibrinogen was limited to the mark-edly thickened endothelial layers of arteries. More ex-tensive intense deposition of both AHF antigen and fibrinogen in glomeruli and in arterial walls were present in hyperacute renal homograft rejection, hemolytic-uremic syndrome, postpartum renal failure, and in some cases of acute homograft rejection. In contrast, deposi-tion of fibrinogen was observed in glomerular epithelial cresents in severe proliferative glomerulonephritis, but AHF deposition was not present in these lesions. Glo-merular deposition of fibrinogen without increased AHF standing was also detected in renal tissue from patients with anaphylactoid purpura nephritis and in recurrent macroscopic hematuria with focal glomerulonephritis. Increased staining of peritubular capillaries with anti-AHF was seen in diseased kidneys irrespective of eti-ology. Immunofluorescent localization of AHF, a par-ticipant in the intrinsic coagulation pathway, offers a new way by which to analyze the mechanisms responsi-ble for fibrinogen deposition in disease