A 26-year-old man, affected by acute non-lymphocytic leukemia, received a bone marrow transplantation from his HLA identical sister. A mild (grade 1) acute graft-versus-host disease (GVHD) developed during the first month after BMT. A moderate (grade 2) muco-cutaneous GVHD was present from the 4th month on, in association with recurrent oral herpes simplex infection. A typical clinical and electromyographic picture of myasthenia gravis (MG) developed 46 months after BMT, requiring continuous medication with pyridostigmine. A high titer of antibiotics against the acetylcholine receptor was found in the serum of the patient but not in the serum of the donor. Since the donor had no evidence of MG or other autoimmune disorders, this is likely to be an autoimmune complication of chronic GVHD. Other cases described in the literature are reviewed: a recurrent expression or coexpression of some HLA antigens was recorded, indicating that some genetic factors could predispose to this acquired disorder.
