Gastric graft-versus-host disease revisited: does proton pump inhibitor therapy affect endoscopic gastric biopsy interpretation?

Accurate diagnosis of gastrointestinal graft-versus-host disease (GvHD) is important, as it contributes significantly to postallogeneic stem cell transplant (SCT) morbidity and mortality. To test the hypothesis that proton pump inhibitor (PPI) therapy may interfere with histologic evaluation of gastric GvHD by inducing apoptosis, we evaluated epithelial apoptotic body counts in antral and fundic biopsies from SCT recipients and control patients, both taking and not taking PPIs at the time of endoscopic biopsy. Hematoxylin and eosin-stained slides of gastric biopsies from 130 patients (75 allogeneic SCT with GvHD on clinical and histologic grounds, and a comparison group of 55 age- and sex-matched nontransplant patients with histologically normal gastric biopsies) were reviewed. The groups were further stratified into patients taking (PPI+) and not taking PPIs (PPI-) at the time of biopsy. Apoptotic bodies (AB)/10 (400 x) high power fields (HPF) were quantified for each case. Mean apoptotic body counts were then calculated for each case group. Seventy antral cases (31 control and 39 transplant) were also evaluated via gastrin immunohistochemistry, and the mean number of gastrin positive cells/400 x HPF calculated. In the PPI- groups, apoptosis was increased in biopsies from transplant patients, compared with controls, both in antral and fundic mucosa. In PPI+ patients, there was significantly more apoptosis in the gastric body in transplant patients than in controls. However, comparing antral biopsies from control and transplant PPI+ patients, there was no significant difference in AB quantitation. More apoptosis was seen in antral biopsies from PPI+ control patients when compared with PPI- control patients (P = 0.009). Mean numbers of gastrin positive cells/400 x HPF were increased in both control and transplant patients taking PPIs (85 and 58, respectively) compared with samples from those patients not taking PPIs (48 and 51, respectively). PPI therapy is associated with increased apoptosis in antral biopsies and may interfere with the evaluation of GvHD in biopsies from this site. A similar increase in apoptosis was not seen in fundic biopsies; biopsy of the gastric fundus rather than antrum may be preferable for the diagnosis of upper gastrointestinal GvHD.