Emerging role of bystander T cell activation in autoimmune diseases

BMB Rep. 2022 Feb;55(2):57-64. doi: 10.5483/BMBRep.2022.55.2.183.


Autoimmune disease is known to be caused by unregulated selfantigen-specific T cells, causing tissue damage. Although antigen specificity is an important mechanism of the adaptive immune system, antigen non-related T cells have been found in the inflamed tissues in various conditions. Bystander T cell activation refers to the activation of T cells without antigen recognition. During an immune response to a pathogen, bystander activation of self-reactive T cells via inflammatory mediators such as cytokines can trigger autoimmune diseases. Other antigen-specific T cells can also be bystander-activated to induce innate immune response resulting in autoimmune disease pathogenesis along with self-antigen-specific T cells. In this review, we summarize previous studies investigating bystander activation of various T cell types (NKT, γδ T cells, MAIT cells, conventional CD4+, and CD8+ T cells) and discuss the role of innate-like T cell response in autoimmune diseases. In addition, we also review previous findings of bystander T cell function in infection and cancer. A better understanding of bystander-activated T cells versus antigenstimulated T cells provides a novel insight to control autoimmune disease pathogenesis. [BMB Reports 2022; 55(2): 57-64].

Publication types

  • News
  • Review

MeSH terms

  • Autoimmune Diseases* / etiology
  • CD8-Positive T-Lymphocytes* / metabolism
  • Cytokines / metabolism
  • Humans
  • Immunity, Innate
  • Lymphocyte Activation


  • Cytokines