Determination of the presence of interleukin-6 in bile after orthotopic liver transplantation: Its role in the diagnosis of acute rejection

Objective: The authors evaluated the significance of interleukin-6 (IL-6) in bile in the diagnosis of acute rejection after liver transplantation. Summary Background Data: Interleukin-6 in blood has not been shown to be useful as a marker of acute rejection in clinical liver transplantation. In a rat liver transplantation model, the authors have found that bile IL-6 levels correlated well with the severity of rejection as determined histologically, whereas kinetics of serum IL-6 differed among rats without any definite feature related to graft rejection. Methods: Fifty-one patients who underwent orthotopic liver transplantation between May 1990 and February 1991 at the University of California, Los Angeles, were included in the study. After liver transplantation, bile and blood were collected daily, and IL-6 levels were measured by the enzyme linked immunosorbent assay. Results: Bile IL-6 increased to 1228 ± 317 pg/mL on the day of transplantation and decreased to 50 pg/mL or less within 48 hours. Patients who had uneventful postoperative courses had low levels of bile IL-6 throughout their hospitalization. In patients with acute rejection, bile IL-6 significantly increased (1090 ± 990 pg/mL; p < 0.05), but decreased in response to antirejection therapy. In patients who had liver dysfunction due to ischemic change or sepsis, bile IL- 6 did not increase. Patients with cholangitis had significantly increased levels of bile IL-6 (146 ± 47; p < 0.05). Interleukin-6 in blood increased with many kinds of complications other than rejection and seemed to be less specific than that in bile. Conclusions: Measurement of IL-6 in bile may be a useful, noninvasive tool for diagnosing acute rejection.