title: Serum citrulline and rejection in small bowel transplantation: a preliminary report.
abstract: BACKGROUND
  There is no known serum marker for intestinal rejection. Serum concentrations of the amino acid citrulline arise almost exclusively from the intestinal mucosa. We examined the impact of acute cellular rejection (ACR) of intestinal allografts on serum citrulline levels.
  
  
  METHODS
  Citrulline concentrations were assayed in serum samples of healthy volunteers (n=6) and seven patients who underwent small bowel transplants (SBTx). Trends in mean citrulline concentrations versus degree of ACR were assessed by matching posttransplantation citrulline concentrations with patients' grade of ACR at time of serum collection. Rejection was confirmed by biopsy and graded by following standardized criteria. An additional patient had citrulline concentrations determined for 31 sequential specimens 3-60 days posttransplant.
  
  
  RESULTS
  Mean citrulline concentrations in controls were significantly higher than posttransplantation samples at any rejection grade. Mean concentrations declined significantly as rejection severity increased. The overall downward trend was statistically significant (P<0.05). In sequential measurements, citrulline levels increased significantly over time with declining severity of rejection. The increase in mean citrulline concentration between posttransplant days 3-16 and 52-60 was significant (P<0.01).
  
  
  CONCLUSIONS
  Serum citrulline levels decline with increasing grade of ACR and may be a useful serum marker for intestinal rejection.
authors.affiliation: Department of Surgery, University of Miami School of Medicine, Highland Professional Building, 1801 NW 9th Ave., Suite 511 Miami, FL 33136, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Pappas
authors.forename: J M
authors.initials: JM
authors.lastname: Saudubray
authors.forename: A G
authors.initials: AG
authors.lastname: Tzakis
authors.forename: D
authors.initials: D
authors.lastname: Rabier
authors.forename: M R
authors.initials: MR
authors.lastname: Carreno
authors.forename: O
authors.initials: O
authors.lastname: Gomez-Marin
authors.forename: F
authors.initials: F
authors.lastname: Huijing
authors.forename: B
authors.initials: B
authors.lastname: Gelman
authors.forename: D M
authors.initials: DM
authors.lastname: Levi
authors.forename: J R
authors.initials: JR
authors.lastname: Nery
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.forename: N
authors.initials: N
authors.lastname: Mittal
authors.forename: S
authors.initials: S
authors.lastname: Nishida
authors.forename: J F
authors.initials: JF
authors.lastname: Thompson
authors.forename: P
authors.initials: P
authors.lastname: Ruiz
mesh_terms: D000328:Adult; D001706:Biopsy; D002675:Child, Preschool; D002956:Citrulline / Q000097:blood*; D006084:Graft Rejection / Q000097:blood* / Q000473:pathology; D006801:Humans; D007223:Infant; D007421:Intestine, Small / Q000473:pathology / Q000637:transplantation*; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D012016:Reference Values; D012189:Retrospective Studies
chemical_list: D002956:Citrulline