Anàlisi estructural de la funcionalitat de CD: com molècula presentadora d'antigen i com diana molecular de reconeixement per les cèl·lules NKT

NKT cells constitute a T cell specific population characterized by the expression of the NK1.1 receptor of Natural Killer cells and an invariant TCR V& chain, both in mouse and human (V&14J&15 i V&24Q&, respectively). This restricted receptor is specifically designed by nture to recognize CD1d, the only CD 1 isotype found in all especies analyzed todate.The CD1 family, which is structurally and functionaly related to MHC presenting molecules, specializes in presenting glycolipids to antigen specific T cells. The CD1d isotype has an unique functionality in the inmune system as it is recognized in an autoreactive way by NKT cells, being this modulated by endogenous glycolipids bound in endocytic compartments. NKT cells respond to CD1d+cells by secreting TH 1 and Th2 tuype interleukines whose ratio, which depends either on the nature of endogenous ligands or on environmental conditions, regulates the inmune response of the organism with special implications in autoinmune responses. Due to its tyrosine motif inthe cytoplasmic tail that regulates intracellular traffic, CD1d is internalized to the more mature compartments of the endocytic system, where processed endogenous glycolipids recognized by NKT cells are presumably bound. We aim to characterize the specificity of the NKT recognition at the molecular level, both in the direct interacion with CD1d and in its putative modulatio by the endogenous ligands constitutively presented by CD1d.