Human tyrosine kinase 2 deficiency reveals its requisite roles in multiple cytokine signals involved in innate and acquired immunity

Immunity. 2006 Nov;25(5):745-55. doi: 10.1016/j.immuni.2006.09.009.


Tyrosine kinase 2 (Tyk2) is a nonreceptor tyrosine kinase that belongs to the Janus kinase (Jak) family. Here we identified a homozygous Tyk2 mutation in a patient who had been clinically diagnosed with hyper-IgE syndrome. This patient showed unusual susceptibility to various microorganisms including virus, fungi, and mycobacteria and suffered from atopic dermatitis with elevated serum IgE. The patient's cells displayed defects in multiple cytokine signaling pathways including those for type I interferon (IFN), interleukin (IL)-6, IL-10, IL-12, and IL-23. The cytokine signals were successfully restored by transducing the intact Tyk2 gene. Thus, the Tyk2 deficiency is likely to account for the patient's complex clinical manifestations, including the phenotype of impaired T helper 1 (Th1) differentiation and accelerated Th2 differentiation. This study identifies human Tyk2 deficiency and demonstrates that Tyk2 plays obligatory roles in multiple cytokine signals involved in innate and acquired immunity of humans, which differs substantially from Tyk2 function in mice.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Base Sequence
  • Cytokines / immunology*
  • Flow Cytometry
  • Humans
  • Immunity, Innate*
  • Immunoblotting
  • Immunologic Deficiency Syndromes / genetics
  • Immunologic Deficiency Syndromes / immunology*
  • Immunologic Deficiency Syndromes / physiopathology
  • Infant
  • Job Syndrome / immunology
  • Male
  • Molecular Sequence Data
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / immunology*
  • TYK2 Kinase / deficiency*
  • TYK2 Kinase / genetics


  • Cytokines
  • TYK2 Kinase