Laboratory assessment of immune function in renal transplant patients

Background. Advances in immunosuppression have made renal transplantation an effective therapy for end stage renal failure; with low rejection rates and long graft survival times. However, the major adverse consequences, infection and malignancy have not diminished. To predict this risk a score of immune competence has been developed from the simultaneous laboratory assessment of multiple parameters of immune function. Methods. The immune status of 152 transplant recipients (138 renal and 14 pancreas/renal) was assessed by measurement of lymphocyte subsets, mitogen-induced T-cell proliferative responses, neutrophil phagocytic capacity and reactive oxygen species (ROS) generation. A scoring system was devised based on the average number of these parameters below 10th percentile of normal. Results. The most common abnormality was B-cell lymphopenia (85%) followed by reduced neutrophil ROS production (63% of patients), NK cell lymphopenia (50%), lymphocyte mitogen response (49%) and CD4 number (23%). The abnormalities were unrelated to the duration of immunosuppression (up to 15 years), and variable combinations of cyclosporine A, azathioprine, prednisolone and mycophenolate mofetil (MMF) (except for a consistent reduction in lymphocyte mitogen response in MMF treated patients). Retrospective comparison of infective episodes showed a significantly greater index of infections in patients with the worst score compared with a normal score. Conclusions. The data suggests that this quantification of immune function may allow assessment of the level of host immune defence reflecting the level of drug-induced immunosuppression and thus risks of immunosuppressive complications.