2.1. Serum

Blood samples were obtained from three healthy controls and three patients according to the guidelines established by the institutional review board of the Taipei Medical University Hospital (N201804015). Patients with a clinical diagnosis of adult-onset immunodeficiency, including disseminated infections with opportunistic pathogens, NTM infections, and HIV-negative status, were enrolled in the study, and the diagnosis of anti-IFN-γ autoAbs has been defined previously [14]. Briefly, a modified sandwich ELISA, adapted from a commercial human IFN-γ sandwich ELISA kit (R&D Systems, Minneapolis, MN), was used to detect anti-IFN-γ autoAbs in the study. In capturing anti-human IFN-γ-coated microwells, the wells were blocked with 0.5% bovine serum albumin (BSA) in phosphate-buffered saline (PBS) Tween 20 buffer and then recombinant human IFN-γ and tested sera were added. The binding of anti-IFN-γ autoAbs was measured by HRP-conjugated detection Abs against human IgG according to the manufacturer's instructions.