y Dis. 2000;35(4):E13-E14 Fig 1. Tubulitis, ie, infiltration of tubular epithelium by lymphocytes, is the hallmark of type I interstitial acute rejection. Different classifications have been put forth for diagnosis of acute rejection. Among the most widely used are Banff, most recently revised in 1997 (published in Kidney International 1999), and CCTT (published in the Journal of the American Society of Nephrology 1998). The lower threshold for rejection by CCTT criteria is 5% of non-scarred parenchyma involved with tubulointerstitial lymphoplasmacytic infiltrate, with tubulitis in at least three tubules, with accompanying tubular injury, lymphocyte activation, and/or edema (at least 2 of these latter 3). In this biopsy, there is tubular injury, edema, and multiple lymphocytes infiltrating under the glomerular basement membrane. (Jones’ Silver Stain, original magnification 3400).