Corticosteroids or steroids are useful drug in clinical renal transplantation because of multiple effects in immunosuppression. There are not a few renal transplant recipients who need steroid therapy, although various new immunosuppressive drugs have developed. However, steroid dosage should be kept as low as possible and preferably withdrawn, because adverse effects of steroids are the most problematical in immunosuppressive drugs. The individual difference of efficacy and adverse effects of steroids depends on pharmacodynamics factor. We have been tried to resolve the dual nature of steroid therapy by steroid sensitivities test using peripheral blood mononuclear cell(PBMC). We clarified significant relationship in steroid sensitivity and clinical outcome, relative immunosuppressive efficacy of steroid, availability of methylprednisolone as immunosuppressive drug, utility for selecting patients who can sustain steroid withdrawal, and pharmacodynamic interaction of calcineurin inhibitors and steroids. We describe here not only results of pharmacodynamic research of steroid sensitivity test, but also comprehensive issues, i. e., history of steroid therapy in renal transplantation, action mechanism of steroid and factor of individual difference of steroid sensitivity, pharmacokinetics of steroid, suppression of hypothalamic-pituitary-adrenal system and immune system, adverse effects of steroid, and practice toward optimal steroid therapy for individual renal recipients.
