[Tubulo-interstitial lesions in human renal allograft]

Tubulo-interstitial lesions developed in renal allografts are divided to two major categories, i.e., primary group specific for renal allografts consisting of rejection, cyclosporine nephrotoxicity and post-transplant acute tubular necrosis, and secondary group accompanied with nephron atrophy caused by any kinds of glomerular, interstitial and/or vascular diseases. An international classification for renal allograft biopsy called Banff criteria was proposed and a comparative study using this criteria would be possible in any place of the world hereafter. After a clinical application of potent immunosuppressive agent cyclosporine or taclorimus, acute and chronic rejection related tubulo-interstitial lesions changed to mild and less specific findings for rejection required a new specific diagnostic criteria for chronic rejection. A concomitant lesion with rejection, glomerulonephritis and cyclosporine nephrotoxicity was an ordinary diagnosis in cyclosporine era. New diagnostic methods using immunohistochemistry and electron-microscopy will contribute to a new and sophisticated pathologic classification for tubulo-interstitial lesions of renal allografts.