Sensorimotor neuropathy resembling CIDP in patients receiving FK506.

FK506 is an important immunosuppressant that has shown great promise in the treatment of autoimmune diseases. Approximately 5% of patients receiving FK506 develop major central nervous system toxicity, but the peripheral nerves are usually spared. During 1990-1991, some 1000 patients received liver transplants under FK506 immunosuppression. Of these, 3 patients developed severe multifocal demyelinating sensorimotor polyneuropathy 2-10 weeks after initiation of FK506 therapy. Improvement followed plasmapheresis or intravenous immunoglobulin (IVIG), suggesting an immune-mediated cause. Although autoimmune neuropathy has been previously reported in immune-deficient states such as Hodgkin's disease and AIDS, it is not an expected complication of immunosuppressive therapy. However, others have shown that this phenomenon can be produced in rats with cyclosporine A (CsA), whose effects on T-cell subsets are similar to those seen with FK506. These T-cell subset changes may have precipitated this dysimmune neuropathy in our patients.