Anti–IFN-γ autoantibodies with high inhibitory activity in patients with dNTM infections. (A) IFN-γ was barely detected in the WB of patients with dNTM infections when stimulated with live BCG or BCG + IL-12. (B) In the absence of patient plasma, the production of IFN-γ was detectable. (C) Patient plasma was serially diluted and incubated with 100 pg/mL of IFN-γ. Plasma from healthy donors (control) and patients with isolated pulmonary NTM infection (isoNTM) showed minimal blocking activity for the detection of IFN-γ. However, plasma from patients with dNTM infections at dilutions of up to 1/106 inhibited the detection of IFN-γ. The data from 2 independent experiments with similar results were combined. (D) Anti–IFN-γ autoantibodies were identified as IgG antibodies. IFN-γ was immobilized by capture antibodies on an ELISA plate and plasma samples from patients and controls were added to the wells. Antibodies to human IgG were added to measure the binding of human IgG autoantibodies to human IFN-γ.
