Extra-tubular deposits of Tamm-Horsfall protein in renal allografts.

Sections from 266 renal allografts that had been transplanted and removed were studied to determine the prevalence of deposits of Tamm-Horsfall protein outside tubules and resulting from tubular rupture, detected by the periodic acid-Schiff (PAS) reaction. The PAS-positive material was shown to be Tamm-Horsfall protein by an indirect immunoperoxidase method. Deposits were found in 152 kidneys (57.1 per cent.), and were commonest at the cortico-medullary junction and in arcuate veins. Deposits were rarely associated with thrombosis or an inflammatory response, and often contained tubules that were reforming. The lesions were rare in grafts totally infarcted from occlusion of the main vessels. Deposits were mostly found in kidneys that had tubular damage from acute rejection reactions, often with ureteric damage, but a few had ureteric obstruction alone. Old deposits were identified in kidneys showing chronic vascular rejection. No features of the deposits themselves could separate cases with ureteric obstruction alone from the other cases. Not every case with ureteric obstruction had the lesions. Extra-tubular deposits of Tamm-Horsfall protein are common in renal allografts and only rarely indicate a specific, surgically-correctable cause of graft dysfunction, namely ureteric obstruction.