Comparison of the Pharmacological Efficacies of Immunosuppressive Drugs Evaluated by the ATP Production and Mitochondrial Activity in Human Lymphocytes.

The lymphocyte immunosuppressant sensitivity test (LIST) using patient peripheral lymphocytes can predict the therapeutic efficacy of immunosuppressive drugs used in renal transplantation. We have evaluated the pharmacological efficacy of drugs by using the LIST with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, which measures the cellular mitochondrial activity. The LIST with the MTT assay requires a relatively large amount of blood. As such, we developed a new assay for examining drug sensitivity with a CellTiter-Glo assay, which measures the amount of cellular ATP to help increase the assay's sensitivity and reduce the amount of blood needed. Renal transplant recipients generally receive either cyclosporine or tacrolimus, in addition to mycophenolate mofetil and methylprednisolone, as an immunosuppressive therapy to prevent acute rejection. We evaluated the pharmacological efficacy of these immunosuppressive agents with both the MTT and CellTiter-Glo assays using the peripheral blood mononuclear cells of 21 healthy volunteers. Furthermore, we also examined the relationship between these immunosuppressive agents' pharmacological efficacy and the results of the MTT and CellTiter-Glo assays. The IC50 values for cyclosporine, tacrolimus, mycophenolic acid, and methylprednisolone were significantly correlated between the MTT and CellTiter-Glo assays. The amount of blood cells required for LIST with the CellTiter-Glo assay was able to be reduced to 25% of the amount required for the previously established LIST with the MTT assay procedure. We concluded from these observations that the LIST with the CellTiter-Glo assay should be used instead of the MTT assay for carrying out individualized immunosuppressive therapy in renal transplantation patients.

Peripheral Lymphocyte Response to Mycophenolic Acid In Vitro and Incidence of Cytomegalovirus Infection in Renal Transplantation.

The lymphocyte immunosuppressant sensitivity test (LIST) with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay procedure has been used to predict the pharmacological efficacy of immunosuppressive agents to prevent acute rejection episodes for renal transplant recipients. In this study, mycophenolic acid (MPA) pharmacological efficacies were evaluated by LIST at both prior to and just after renal transplantation. We compared the efficacies to the clinical outcome of these recipients. MPA's pharmacological efficacy was evaluated by LIST not only before the operation but also at 2, 4, and 6 weeks after transplantation in 16 renal transplant recipients. These recipients were divided into high- and low-sensitivity groups according to peripheral blood mononuclear cell (PBMC) sensitivity to MPA in vitro. The MPA sensitivities were compared to cytomegalovirus (CMV) infection and acute rejection episodes in these recipients under MPA immunosuppressive therapy. The rate of CMV infection episodes in the low-MPA pharmacological efficacy group categorized at 2 weeks after renal transplantation was 5/6 (83.3%), which was significantly higher than the rate of 1/10 (10.0%) (p < 0.01) in the high-MPA sensitivity group. However, the MPA pharmacological efficacy evaluated both before and after transplantation had no relationship with the incidence of rejection episodes. These findings suggest that the MPA pharmacological efficacy evaluated by LIST at 2 weeks after operation is a useful biomarker for predicting the following occurrence of CMV infection episodes in renal transplant recipients.

Comparative study of the cellular pharmacodynamics of tacrolimus in renal transplant recipients treated with and without basiliximab.

Basiliximab is a recently developed immunosuppressive agent for the prevention of acute allograft rejection in renal transplant recipients. The combination use of basiliximab and a calcineurin inhibitor was suggested to be more effective in comparison to immunosuppressive therapy using calcineurin inhibitor without basiliximab. Cyclosporine has been generally administered with basiliximab for renal transplant recipients. However, in cases of tacrolimus-based immunosuppressive regimen, the clinical efficacy and safety of combined use of tacrolimus and basiliximab remains to be elucidated. This study evaluated the tacrolimus pharmacological efficacy using a lymphocyte immunosuppressant sensitivity test (LIST) with MTT assay procedures in 16 cases of renal transplant recipients treated by tacrolimus without basiliximab and in 13 cases treated by tacrolimus in combination with basiliximab. The rate of acute rejection episodes in the recipients treated with tacrolimus plus basiliximab was 1/13 (7.7%), whereas the rate in the recipients treated with tacrolimus without basiliximab was 6/16 (37.5%). The recipients were divided into two groups according to their peripheral blood mononuclear cell (PBMC) sensitivity to tacrolimus [i.e., including a tacrolimus high sensitivity group (IC(50) <1.0 ng/ml) and a low sensitivity group (IC(50) >1.0 ng/ml). In the recipients treated with tacrolimus without basiliximab, the rate of acute rejection episodes in the tacrolimus high sensitivity group was 1/10 (10.0%), which was significantly lower than the rate in the low sensitivity group of 5/6 (83.3%; p = 0.008). The incidence of cytomegalovirus infection was not significantly different between the tacrolimus high and the low sensitivity groups of the recipients treated with tacrolimus with and without basiliximab. Therefore, in the case of selected tacrolimus-based immunosuppressive therapy for renal transplant recipients, the tacrolimus pharmacological efficacy should be evaluated using LIST at a time just before the transplant procedure in order to accurately predict allograft rejection. The data also suggested that low tacrolimus sensitivity recipients should be treated with tacrolimus-based immunosuppressive therapy in combination with basiliximab.

Clinical Significance of the Pharmacological Efficacy of Tacrolimus Estimated by the Lymphocyte Immunosuppressant Sensitivity Test (LIST) Before and After Renal Transplantation.

The lymphocyte immunosuppressant sensitivity test (LIST) with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay procedure can predict the pharmacological efficacy of immunosuppressive agents. A previous study reported the pharmacological efficacy of tacrolimus evaluated by LIST just before renal transplantation significantly correlated with the incidence of acute rejection episodes. However, the pharmacological efficacy of tacrolimus has not been estimated after renal transplantation. Therefore, the present study evaluated the pharmacological efficacy of tacrolimus by LIST using the MTT assay procedure before and 1, 3, and 12 months after transplantation in 17 renal transplant recipients that received tacrolimus-based immunosuppressive therapy. The tacrolimus pharmacological efficacies before and after the procedure were also compared with incidence of acute rejection and cytomegalovirus (CMV) infection episodes. The individual values of tacrolimus 50% inhibition of lymphocyte proliferation (IC50) varied widely before transplantation, and the mean value of the IC50 was 126.4 ± 337.7 ng/ml. The patients were divided into two groups according to the tacrolimus IC50 values evaluated before transplantation. The rate of acute rejection episodes in the tacrolimus high-sensitivity group was significantly lower than that in the tacrolimus low-sensitivity group (p = 0.005). The tacrolimus IC50 deviation between patients expanded further at one and three months after surgery. However, the sensitivity deviation almost converged at 1 year after surgery. Moreover, the pharmacological efficacy of tacrolimus evaluated at 1, 3, and 12 months after transplantation did not significantly correlate with the incidence of acute rejection episodes. The pharmacological efficacies of tacrolimus evaluated at both before and after surgery were not significantly correlated with the episodes of CMV infection. These findings suggest that the pharmacological efficacy of tacrolimus evaluated with LIST before surgery is a useful biomarker for predicting the occurrence of acute allograft rejection in renal transplantation.

The pharmacological efficacy of mycophenolic acid before and after renal transplantation as estimated by the lymphocyte immunosuppressant sensitivity test (LIST).

The lymphocyte immunosuppressant sensitivity test (LIST) can predict the pharmacological efficacy of immunosuppressive agents. We herein estimated the mycophenolic acid efficacy using LIST before and 1, 3, and 12 months after the operation in 15 renal transplant recipients. The pharmacological efficacy of mycophenolic acid as assessed before transplantation showed small individual variations, whereas the variability greatly increased at 1 and 3 months after transplantation. Furthermore, the individual IC50 variation among these subjects at 1-year after operation was closely similar to that observed before surgery. No significant implications of these individual differences in the mycophenolic acid sensitivity were noted in regard to the clinical courses of these recipients.

Pharmacodynamic parameters of immunosuppressive drugs are not correlated with age, duration of dialysis, percentage of lymphocytes or lymphocyte stimulation index in renal transplant recipients.

The lymphocyte immunosuppressant-sensitivity test (LIST) has been reported extensively as being able to estimate the pharmacological efficacy of immunosuppressive drugs in individual patients. This study measured the IC50 values for 6 drugs, cyclosporine, tacrolimus, methylprednisolone, 6-mercaptopurine, mycophenolic acid, and mizoribine, against mitogen-induced proliferation of peripheral-blood lymphocytes in 29 renal transplant recipients. We also examined relationship between the IC50 values and 4 factors; age, duration of dialysis, percentage of lymphocytes in total white blood cells, and blastogenesis stimulation index by mitogen. There were no significant correlations between the IC50 values and these factors, except that the tacrolimus IC50 value was correlated weakly with the stimulation index (p<0.05, r=-0.429). It was concluded that the pharmacological efficacy of immunosuppressive drugs cannot be inferred from the patient characteristics or their laboratory data. LIST is an effective method to elucidate the pharmacodynamic properties of immunosuppressive agents in individual renal transplant recipients without being influenced by the recipient clinical data.