A possible serum marker for rejection after small intestine transplantation.

Frequent histologic evaluation of mucosal biopsies remains the most reliable method of monitoring and diagnosing rejection after small intestine transplantation, but lengthy processing time can result in delay in diagnosis. Unfortunately, a serum marker for monitoring small intestine transplantation rejection has not been identified. Hexosaminidase, a lysosomal acid hydrolase, has been shown to increase in serum in association with intestinal ischemia, a finding also associated with acute rejection after small intestine transplantation. We measured N-acetyl hexosaminidase levels after transplantation in three groups of five rats each as follows: Group I, Lewis strain small intestine to Lewis recipients; Group II, Wistar small intestine to Lewis recipients; and Group III, Wistar small intestine to Lewis recipients treated with 25 mg/kg per day of cyclosporine. Serum N-acetyl hexosaminidase levels and mucosal biopsies were obtained on days 0, 2, 4, 6, 8, 10, 12, 14, and 21. Rats in Groups I and III survived without gross evidence of rejection. Three rats in Group II died between 8 and 10 days, and serum N-acetyl hexosaminidase levels increased 24 to 48 hours before death. In the remaining Group II rats, the N-acetyl hexosaminidase levels were significantly higher on days 10, 12, and 14 after transplantation (p less than 0.05). In two of five rats, the histologic changes of rejection occurred later than the increase in N-acetyl hexosaminidase levels. Because measurement of N-acetyl hexosaminidase levels is a rapid and simple serum assay, it may be useful for monitoring rejection after small intestine transplantation.