Role of invariant nkt cells in the anti-viral immune response.

Abstract

Natural killer T cells with an invariant T-cell receptor and restricted by CD1d (iNKT) are a subgroup of lymphocytes with a very strong immunoregulatory potential; their quick response and their ability to produce Th1 and Th2 cytokines are determinant factors that influence the development of innate and adaptive immune responses. The physiological role of iNKT cells has been well documented in anti-tumor immune responses, the development of tolerance in immune-privileged organs and the control of autoimmune diseases. Despite the fact that the immunoregulatory potential of these cells has been well documented, less is known regarding their role in the immune response against infectious agents, in particular to human pathogenic viruses. This paper synthesizes the search in the most important biomedical data bases (Pubmed, Medline, OVID), including studies on the phenotypic characterization of these cells and functional studies that evaluated their role in the interaction between hosts and viruses. iNKT cells have a heterogeneous participation during the anti-viral immune responses, depending on the type of virus; indeed, in some instances the iNKT-cell responses can be involved in the tissue damage associated to the anti-viral responses. In humans, iNKT cells are apparently essential for an effective immune response against Varicella Zoster virus, while it is still controversial their role in the control of other viral infections. Studies in animal models have shown the first evidences on the therapeutic potential of this lymphocyte subpopulation.