Severe aplastic anemia with autoimmune thyroiditis showing no hematological response to intensive immunosuppressive therapy.

A 39-year-old woman with severe aplastic anemia (SAA) was transferred to our institution. She also had autoimmune thyroiditis with several positive autoantibodies. Clonal or oligoclonal T-cell proliferation was demonstrated by determining the size distribution of the complementarity-determining region 3 (CDR3) of T-cell receptor beta-chain (TCR-Vbeta) subfamilies in the patient's bone marrow and peripheral blood cells. The results suggested that hematopoiesis was suppressed by immune-mediated mechanisms. Immunosuppressive therapy for SAA using cyclosporin A (CsA) alone or concurrent CsA and antithymocyte globulin (ATG) failed to induce a hematological response. The intensity of the autoantibodies, however, partially decreased during this period. In addition, the CD4/CD8 ratio was inverted after immunosuppressive therapy. These observations indicate that, in a subset of SAA, immune-mediated hematopoietic suppression cannot be successfully treated by conventional immunosuppressive therapy, even though a substantial improvement in the underlying immunological changes can be achieved. Other therapies such as hematopoietic stem cell transplantation or more intensified repeated ATG therapy may be necessary for such patients.