Page 601 - Veterinary Immunology, 10th Edition

VetBooks.ir NKT Cells

Natural killer T cells (NKT cells) are innate-like T cells that express
both NK cell markers and a TCR of limited diversity. There are two

functionally distinct NKT cell subsets. Type I NKT cells are T cells
that express a semi-invariant TCR consisting of an invariant α chain
associated with diverse β chains. This TCR recognizes lipid,
lipopeptide, and glycolipid antigens presented by the MHC class I-
like molecule CD1. CD1 proteins are nonpolymorphic molecules

found on antigen-presenting cells (Fig. 19.14). The CD1-lipid
presentation system allows the immune system to sense lipid
antigens. It thus complements the MHC-peptide presentation

system. Some CD1 proteins present lipid antigens to conventional T
cells, while others present lipids to NKT cells. Type I NKT cells can
promote immunity in response to lipid antigens from infectious
agents and tumor cells. They are found in the liver, spleen, blood,
and adipose tissue. Most are found in the sinusoids of the liver.

They make up about 1% of the mononuclear cells in human blood.

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