• 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.
  • 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
  • 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
  • Serology
    • IFN-γ
Differential Diagnosis
  • IFN-γ receptor deficiencies
  • Hyper IgE syndrome
  • 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

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