Disease specificity of anti-tryptophan hydroxylase-1 and anti-AIE-75 autoantibodies in APECED and IPEX syndrome

•Anti-AIE-75 antibodies are detected in IPEX syndrome but not in APECED.•Anti-TPH-1 antibodies are detected in APECED but not in IPEX syndrome.•Autoantibodies could differentiate GI dysfunction associated with IPEX syndrome or APECED.

Autoantibodies to autoimmune enteropathy-related 75 kDa antigen (AIE-75) and villin are disease markers of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome which is characterized by a peripheral tolerance defect. On the other hand, anti-tryptophan hydroxylase-1 (TPH-1) antibodies are detected in autoimmune polyendocrinopathy, candidiasis, ectodermal dystrophy (APECED), a central tolerance defect, especially when complicated with gastrointestinal dysfunction. However, to date, anti-AIE-75 and anti-villin antibodies or anti-TPH-1 antibodies have not been tested in APECED or IPEX syndrome, respectively. In the present study, we confirmed the disease specificity of both anti-AIE-75 and anti-TPH-1, although anti-villin antibodies were detected in some patients with APECED. Our observation suggests that immunotolerance to AIE-75 depends on the peripheral mechanism, whereas the tolerance to TPH-1 depends on the central mechanisms.