The role of mucosal biopsy in the monitoring of pediatric intestinal a
llografts is analyzed. We performed a retrospective review of all biop
sy, resection, and autopsy material from 22 bowel allografts in 21 pat
ients, followed from 6 months to 3 1/4 years and treated on an immuno-
suppressive regimen based on FK 506 (Tacrolimus). There were 579 biops
ies, of which 35 were stomal, with two to three fragments taken at eac
h biopsy. There were three explanted bowels and three autopsies. Stoma
l biopsies proved to be inappropriate for monitoring. Biopsies with th
ree to five pieces of tissue per site, under endoscopic direction, pro
vided the most information. Early cellular infiltrate with lymphoid ac
tivation in the absence of epithelial apoptotic figures was not consid
ered sufficient to diagnose rejection although preceded it in most ins
tances. At least two apoptotic figures in a gland or several single ap
optotic cells in the presence of a lymphoid infiltrate with activated
lymphoid follicles and prominent endothelium correlate best with clini
cal rejection and response to antirejection measures. Epstein-Barr vir
al disease is common in this population, and early, late, and nonconti
guous bowel involvement can be subtle and difficult to distinguish fro
m rejection, though without the apoptosis. Epstein-Barr virus in situ
probes are essential to make the differential diagnosis and the two co
nditions may co-exist. Mucosal biopsy monitoring appears to be of clin
ical utility and is part of a program that involves clinical, endoscop
ic, microbiological, and morphologic assessment.