Successful immunosuppressive therapy is critical for
liver transplantation. However, a considerable number of patients show clinical resistance to the
therapy and experience rejection episodes, or alternatively exhibits serious adverse effects of drugs. We examined the in vitro response of peripheral blood mononuclear cells (PBMCs) to immunosuppressive drugs in
cirrhosis patients awaiting
liver transplantation. We evaluated the suppressive efficacy of
prednisolone,
methylprednisolone,
cyclosporine, and
tacrolimus on the in vitro blastogenesis of PBMCs obtained from 22
cirrhosis patients and 31 healthy subjects. In vitro drug concentrations giving 50% inhibition of PBMC blastogenesis (IC50s) were calculated. Two out of these 22 patients received
liver transplantation from living donors, and their clinical courses were surveyed until 5 weeks after operation. The median IC50 values for
prednisolone,
cyclosporine, and
tacrolimus against blastogenesis of PBMCs from
cirrhosis patients were significantly lower than those of PBMCs from healthy subjects (p < 0.01). However, large individual differences were observed in the IC50 values of the immunosuppressive drugs examined, especially in the
cirrhosis patients. One recipient exhibiting high PBMC sensitivity to
tacrolimus (IC50 = 0.001 ng/ml) showed good
clinical course without rejection until 5 weeks after
liver transplantation. The other recipient exhibiting relatively low PBMC sensitivity to taclolimus (IC50 = 0.30) showed allograft rejection at 1 week after operation. We concluded from these observations that PBMCs of
cirrhosis patients are vulnerable to the immunosuppressive effects of
prednisolone and
calcineurin inhibitors. However, large individual variations in the IC50 values suggest that patients exhibiting relatively lower sensitivity to these drugs may have risks of rejection, whereas highly sensitive patients are possibly able to reduce the dose of immunosuppressive drugs to avoid serious drug-adverse effects, after
liver transplantation.