Intestinal ischemia/reperfusion injury (I/R) results from reactive oxy
gen metabolites generated by the xanthine oxidase system and activated
neutrophils (PMN). In animal models, removing PMN from initial reperf
usate has consistently decreased tissue injury. This experiment was de
signed to test this potential clinical treatment in human bowel subjec
ted to I/R. The extent of reperfusion injury was assessed by measuring
the activity of mucosal alkaline phosphatase (A phi), which is a spec
ific marker of reperfusion injury. Human small intestine (n = 13) obta
ined at the time of organ harvest for transplantation was perfused for
60 min on an ex vivo perfusion circuit. Reperfusate consisted of auto
logous blood passed through a leukocyte filter (n = 6) or unfiltered b
lood (n = 7). Control intestine was sampled at harvest, after transpor
t to the lab on ice (cold ischemia), and after 60 min warm ischemia. M
ucosa was homogenized and assayed for A phi activity by cleavage of p-
nitrophenyl phosphate. A phi activity (nmole/mg/min) was not decreased
after either cold (774 +/- 37) or warm (753 +/- 40) ischemia compared
to freshly harvested bowel (770 +/- 51). Both reperfused segments sho
wed a significant decrease in A phi activity compared to controls (P <
0.05); however, reperfusion with leukocyte-filtered blood attenuated
the decrease in enzyme activity compared to unfiltered blood (327 +/-
30 vs 506 +/- 25, P < 0.05), constituting an apparent reduction in inj
ury of 35%. The observation that the severity of reperfusion injury wa
s decreased by removal of PMN from the reperfusate demonstrates the ef
ficacy of this strategy in human intestine for the first time. (C) 199
4 Academic Press, Inc.