Role of NKT Cells in the Regulation of Ongoing Type 2 Immune Response

Abstract

The role of NKT cells in the promotion of allergic asthma and helminthiasis will be emphasized and the current understanding on the mechanisms by which N KT cells activate and modulate Th2 immune response will be discussed. CD1d-restricted natural killer T (NKT) cells represent a heterogeneous population of innate/memory immune cells. A striking characteristic of NKT cells is their ability to produce Th1- and/or Th2-type cytokines quickly after primary stimulation with glycolipid antigen presented by antigen-presenting cells in the context of CD1d. Through this property, NKT cells are a unique T lymphocyte subpopulation that has been implicated in the regulation of immune responses associated with a broad range of diseases, including autoimmunity, inflammatory and infectious diseases as well as tumour pathologies. Although their role in regulating Th1 response to self-antigens (autoimmune diseases) or foreign antigens (infectious disease) has been largely described, recent evidence also suggests that NKT cells are implicated in the initiation of some Th2-related inflammatory and infectious diseases, thus underlying the flexibility of this cell population. Here we review the general features of these cells as well as their influence on Th2-associated pathologies. We will particularly emphasize the role of NKT cells in the promotion of allergic asthma and helminthiasis. Our current understanding on the mechanisms by which NKT cells activate and modulate Th2 immune response will be discussed.