Kinetics and cellular site of glycolipid loading control

CD1d-restricted natural killer T cells (NKT cells) possess a wide range of effector and regulatory
activities that are related to their ability to secrete both T helper 1 (Th1) cell- and Th2 cell-type
cytokines. We analyzed presentation of NKT cell activating α galactosylceramide (αGalCer) analogs
that give predominantly Th2 cell-type cytokine responses to determine how ligand structure controls
the outcome of NKT cell activation. Using a monoclonal antibody specific for αGalCer-CD1d
complexes to visualize and quantitate glycolipid presentation, we found that Th2 cell-type cytokinebiasing
ligands were characterized by rapid and direct loading of cell-surface CD1d proteins.
Complexes formed by association of these Th2 cell-type cytokine-biasing αGalCer analogs with
CD1d showed a distinctive exclusion from ganglioside-enriched, detergent-resistant plasma
membrane microdomains of antigen-presenting cells. These findings help to explain how subtle
alterations in glycolipid ligand structure can control the balance of proinflammatory and antiinflammatory
activities of NKT cells.