Acute cellular rejection grading scheme for human gastric allografts

The control of acute cellular rejection (ACR) in multivisceral transplantation improves long-term survival, but monitoring this process can be challenging because different allografts can display varying forms and degrees of rejection. Criteria for ACR of small bowel and liver have been established, but a systematic analysis for ACR in stomach is lacking. For this reason we have developed a comprehensive grading scheme for the evaluation of gastric allograft rejection. The grading scheme was designed to individually grade a variety of changes in the surface epithelium, lamina propria, and glandular structures. The individual values are cumulated, and the final score determines assignment of the rejection grade. The ACR grades range from no evidence of acute cellular rejection to severe rejection. We performed a retrospective study based on 70 gastric allograft biopsies from 20 patients who received multivisceral transplantation from 1995 to 2001. We found that the scoring system showed no significant interobserver variability and allowed for an accurate designation of the ACR grade to the gastric allografts. We found with this grading system that neither clinical symptoms nor gastric endoscopic findings could serve as specific indicators of gastric ACR. Our results also showed that there were differences in the occurrence and intensity of acute rejection between the stomach and other transplanted organs, suggesting that ACR can occur independently among different allografts of the same host. In conclusion, we find that this scheme for grading ACR in gastric transplants is objective and reproducible. This grading system will likely allow for improved correlation between gastric ACR grade and clinical symptoms, as well as improve interobserver uniformity within and between institutions.