Molecular biology of NK T cell specificity and development

NK T cells recognize a glycosphingolipid, alpha -galactosyl ceramide, presented by CD1d. CD1d is capable of binding a variety of lipids, however and the hydrophilic groups of the antigen contribute relatively little to CD1d binding: Amino acids in the CD1d groove and the top of the a helices are involved in lipid antigen presentation, suggesting a conventional mode of presentation and antigen recognition. NK T cells also have unique requirements for their differentiation, as suggested by the analysis of a number of mouse germline mutations. For example, the development of NK T cells, unlike conventional T lymphocytes, is highly lymphotoxin dependent.