Pancreas transplantation under alemtuzumab (Campath-1H) and tacrolimus: Correlation between low T-cell responses and infection

BACKGROUND. Alemtuzumab induction and tacrolimus-based immunosuppression has been effective in pancreas transplantation. Despite the encouraging results of this minimalistic approach to immunosuppression, infection still remains a significant cause of morbidity. The Cylex ImmunoKnow assay was used in this study to compare pancreas recipient clinical states (stable, rejection, infection) with T cell responses. METHODS. Blood samples were taken from pancreas recipients pretransplant and at approximately three-month intervals posttransplant for analysis of T cell responses. When possible, T cell responses were also quantified during changes in clinical status (infection or rejection). RESULTS. A range between 100-300 ng/ml adenosine triphosphate (ATP) was found in stable patients (mean 194±123, n=51) with good graft function and no infection or rejection. A low T cell response was highly correlated with infectious states. The fourteen patients with infections/posttransplant lymphoproliferative disease had a mean ATP of 48 ng/ml. Risk hazard analysis showed that patients with ATP levels <100 ng/ml were four to seven times more susceptible to infection compared to stable patients. Four patients with rejection showed a T cell response of 550 ng/ml ATP, which was statistically significant compared to stable patients, although the sampling numbers (9) were too small to be conclusive. CONCLUSION. The Cylex ImmunoKnow assay is a valuable tool to more precisely modulate immunosuppression in pancreas transplant patients. In particular, the assay is extremely useful in detecting overly immunosuppressed patients vulnerable to infections.