Snapshot A 4-year-old boy is brought to the emergency department with a fever, rigors, hypotension, and dyspnea following BCG vaccine administration. When an IV was attempted, she began bleeding profusely from the site. A CXR showed interstitial infiltrates, raising suspicion for pneumonitis. Blood specimens show acid-fast bacilli. Culture are pending. Empiric treatment with fluoroquinolones is started. Introduction IL-12 function promotes cell-mediated immunity induces maturation of T cells into Th1 cells stimulates macrophages to secrete interferon (IFN)-γ activates NK cells Mutations in IL-12 receptors resulting in decreased IFN-γ Genetics autosomal recessive Pathogenesis impaired Th1 response impaired secretion of IFN-γ leads to disseminated infections Presentation Symptoms recurrent disseminated infections in early childhood non-TB mycobacteria Salmonella disseminated infection after BCG vaccine note granulomatous infections are well contained often present in sepsis (fevers, rigors, hypotension, etc) and DIC infections can also be limited to organs pneumonitis hepatitis Evaluation Serology ↓ IFN-γ Differential Diagnosis IFN-γ receptor deficiencies Hyper IgE syndrome Treatment Antibiotics/antifungals as infections arise IFN-γ therapy may help Prognosis, Prevention, and Complications Prognosis variable prognosis overall mortality rate 30% due to disseminated infections Complications fatal disseminated infections, esp with non-TB Mycobacteria