Molecular biology of NK T cell specificity and development

NK T cells recognize a glycosphingolipid, alpha -galactosyl ceramide, prese nted by CD1d. CD1d is capable of binding a variety of lipids, however and t he hydrophilic groups of the antigen contribute relatively little to CD1d b inding: Amino acids in the CD1d groove and the top of the a helices are inv olved in lipid antigen presentation, suggesting a conventional mode of pres entation and antigen recognition. NK T cells also have unique requirements for their differentiation, as suggested by the analysis of a number of mous e germline mutations. For example, the development of NK T cells, unlike co nventional T lymphocytes, is highly lymphotoxin dependent.