title: Acute tubular injury is an important component in type I acute antibody-mediated rejection.
abstract: BACKGROUND
  "Acute tubular necrosis (ATN)-like" changes in type I acute antibody- mediated rejection (AAMR) have been proposed since 2005, but the presence of "ATN-like" injury in AAMR has not well been established. The aim of this study was to confirm the presence of acute tubular injury in type I AAMR, using the specific proximal tubular injury marker, kidney injury molecule-1 (KIM-1).
  
  
  METHODS
  The study included 3 groups of cases, namely, a negative control group (normal nontransplantation renal parenchyma as group 1, n = 11), a positive control group (transplant ATN with negative C4d staining as group 2, n = 12), and study cases (type 1 AAMR as group 3, n = 19). Biopsy specimens from all groups were stained immunohistochemically for KIM-1 (monoclonal antibody) and KIM-1 staining intensity in proximal tubules was graded from 0.5 to 3+. Clinical indices were also correlated and analyzed.
  
  
  RESULTS
  Group 1 demonstrated significantly lower serum creatinine levels (1.02 ± 0.10 mg/dL) when compared with both group 2 and group 3. Both groups 2 and 3 showed similar serum creatinine levels (4.02 ± 0.59 mg/dL in group 2 and 3.24 ± 0.34 mg/dL in group 3). The negative control group demonstrated negative proximal tubule staining for KIM-1, whereas both groups 2 and 3 showed positive KIM-1 staining in proximal tubules (intensity ranging from 1+ to 3+ in group 2 and from 0.5 to 3+ in group 3).
  
  
  CONCLUSIONS
  Our results, using KIM-1 immunohistochemistry, demonstrated that acute tubular injury is an important component of type I AAMR.
authors.affiliation: Department of Anatomic & Clinical Pathology, William Beaumont Hospital, Royal Oak, Michrgen, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Johnson
authors.forename: D
authors.initials: D
authors.lastname: Sarmarapungavan
authors.forename: R K
authors.initials: RK
authors.lastname: Parasuraman
authors.forename: G
authors.initials: G
authors.lastname: Maine
authors.forename: M T
authors.initials: MT
authors.lastname: Rooney
authors.forename: S C
authors.initials: SC
authors.lastname: Wolforth
authors.forename: G H
authors.initials: GH
authors.lastname: Reddy
authors.forename: S R
authors.initials: SR
authors.lastname: Cohn
authors.forename: F
authors.initials: F
authors.lastname: Dumler
authors.forename: L L
authors.initials: LL
authors.lastname: Rocher
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.forename: P L
authors.initials: PL
authors.lastname: Zhang
mesh_terms: D000906:Antibodies / Q000276:immunology*; D001706:Biopsy; D016022:Case-Control Studies; D006084:Graft Rejection / Q000276:immunology*; D006801:Humans; D007684:Kidney Tubules / Q000473:pathology*
chemical_list: D000906:Antibodies