Use of immune function test in monitoring immunosuppression in liver transplant recipients

Immune function test (Immuknow (TM)) is a measure of cell-mediated immunity based on peripheral CD4(+) T cell adenosine triphosphate activity (desired range, 225-525 ng/mL). We evaluated the role of immune function test (IFT) in monitoring and adjustment of immunosuppression in orthotopic liver transplant (OLT) recipients. A total of 289 IFTs were obtained from 171 patients from March 2007 to June 2008. Graft/patient status was classified as stable, serious infection, or malignancy. IFT levels were analyzed with duration of follow-up after OLT, graft/patient status, and the presence of hepatitis C (HCV) infection. The mean age was 54 +/- 14 yr, with 62% men. The median follow-up was 65 (2-249) months. Mean IFT levels were significantly lower in patients who were <24 months than in those >24 months post-OLT (220 +/- 19.5 vs. 257 +/- 11.3 ng/mL, p = 0.03). Clinically stable patients had higher IFT levels than those with serious infection or malignancy (254 +/- 11.1 vs. 162.5 +/- 23.9, p < 0.001). HCV-infected patients had lower IFT levels than uninfected patients (206.7 +/- 15.7 vs. 273 +/- 12.0 ng/mL, p < 0.001). Immunosuppression was reduced in 58 patients with IFT levels < 225 ng/mL, and 90% maintained stable graft function after a median follow-up of 22 (1-39) months. IFT may be a useful tool in monitoring and lowering of immunosuppression in long-term OLT recipients.