Primary tubulointerstitial nephritis caused by antibodies to proximal tubular antigens

Abstract

Acute oliguric renal failure requiring hemodialysis developed in a 59-year-old man who had myasthenia gravis. A renal biopsy on day 21 was diagnostic of tubulointerstitial nephritis. Despite regular hemodialysis, the patient died of complications 17 weeks after the onset of oliguria. At post-mortem examination, a thymoma was found, and renal histopathology indicated tubulointerstitial nephritis and concomitant generalized epimembranous and intramembranous electron-dense deposits of glomerular capillary walls. By direct immunofluorescence, immunoglobulins and C'3 were visualized in peritubular granular deposits around proximal tubules, but not on glomeruli. The renal acid-eluate contained immunoglobulins that bound to proximal tubule brush border, intracellular cytoplasmic granules, and a granular antigen probably associated with basement membrane of proximal tubule cells of normal human kidney and the patient's kidney, whereas the patient's serum apparently contained antibodies only to proximal tubule brush border. The renal eluate did not bind to normal or the patient's glomeruli, and partial elution of the patient's kidney did not expose new binding sites for the eluate. The data indicate a unique instance of tubulointerstitial nephritis caused by antibodies to multiple proximal tubule antigens apparently forming immune complexes in situ.