Clinical aspects: monitoring of function and rejectionSerum citrulline is a potential marker for rejection of intestinal allografts
Section snippets
Methods
Between 1/1/01 and 2/15/01, nine consecutive intestinal transplant recipients (three isolated, five combined liver-bowel, and one multivisceral; eight children and one adult) were studied (GCO-01-0810). Jejunum or ileal biopsies were performed by protocol or on the basis of clinical course (GIF XP-160 5.9 mm endoscope, Olympus America Inc, Melville, NY, USA). Citrulline levels in extra blood from samples available at the time of the biopsies were analyzed.
One half to 2 mL of heparinized blood
Biopsies
Of 32 biopsies performed in nine patients, 13 (40%) were normal, nine (28%) were indeterminate for rejection, five (15.6%) showed signs of mild acute cellular rejection, two (6.3%) had moderate rejection, and three (9.4%) presented viral enteritis (adenovirus). Twenty-two biopsies showed “functional” bowels (68.8%); 10 showed “dysfunctional” bowel (31.3%).
Citrulline levels
Thirty-two citrulline measurements were made in the nine patients. The mean level was 17.5 ± 13.3 nmol/mL (range, 0.8 to 68 nmol/mL). When we
Discussion
Citrulline synthesis, an energy-demanding process (Km 1.93),6 is an end product of nitrogen metabolism in intestinal mucosal cells. In these cells, the urea cycle is incomplete, because while the mitochondrial enzymes catalyzing citrulline biosynthesis are present, the cytosolic enzymes needed to convert citrulline to arginine are not.3 The intestine is the only tissue that normally releases significant amounts of citrulline into the blood.
Very little of the citrulline released by the intestine
References (6)
- et al.
J Biol Chem
(1980) - et al.
Gastroenterology
(1996) - et al.
Am J Physiol
(1981)