Brush cytology in the course of acute small bowel allograft rejection.

Objective: To examine the changes in brush cytology during acute small bowel allograft rejection and to evaluate the usefulness of cytology in detecting acute rejection.
Study Design: Heterotopic porcine small bowel allografts were followed by brush cytology and full-thickness biopsies during unmodified rejection.
Results: The most prominent changes in cell differential counts were an increase in the proportion of granulocytes and decrease in the proportion of epithelial cells. In brushed epithelial fragments, infiltration of granulocytes and acidophilia increased, and cell cohesion was gradually lost with the degeneration of nuclei and necrosis of epithelium. The cell differential count was compared to the histologic acute rejection index, which was created on the basis of five semiquantitatively evaluated histologic parameters. The sensitivity of cell differentiation in detecting histologically moderate or severe rejection was 87% (13 of 15 cases) and the specificity 76% (5 false positives in 21 negative cases).
Conclusion: Suspicion of acute rejection can be assessed with reasonable reliability by cytology, but it cannot be detected earlier than by histology. Brush cytology complements mucosal biopsies in the evaluation of rejection and, as a rapid and cost-effective method, may even partly replace them. It may also prove valuable in detecting opportunistic bowel infections in immunosuppressed patients.