Inherited disorders of the IL-12-IFN-γ axis in patients with disseminated BCG infection

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Abstract
Disseminated BCG infection is a rare complication of vaccination that occurs in patients with impaired immunity. In recent years, a series of inherited disorders of the IL-12-IFN-γ axis have been described that predispose affected individuals to disseminated disease caused by BCG, environmental Mycobacteria, and non-typhoidal Salmonella. The routine immunological work-up of these patients is normal and the diagnosis requires specific investigation of the IL-12-IFN-γ circuit. We report here the first two such patients originating from and living in Iran. The first child is two years old and suffers from complete IFN-γ receptor 2 deficiency and disseminated BCG infection. He is currently in clinical remission thanks to prolonged multiple antibiotic therapy. The other, a 28-year-old adult, suffers from IL-12p40 deficiency and presented with disseminated BCG infection followed by recurrent episodes of systemic salmonellosis. He is now doing well. A third patient of Iranian descent, living in North America, was reported elsewhere to suffer from IL-12Rβ1 deficiency. These three patients thus indicate that various inherited defects of the IL-12-IFN-γ circuit can be found in Iranian people. In conclusion we recommend to consider the disorders of the IL-12-IFN-γ circuit in all patients with severe BCG infection, disseminated environmental mycobacterial disease, or systemic non-typhoidal salmonellosis, regardless of their ethnic origin and country of residence.