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Session 89 Poster Abstracts
Enhancing Immune Responses to Vaccines
Wednesday, 1:30 - 3:30 pm
Hall D


496    
Novel Bacteria-derived Glycolipids and Sulfatide Analogs Are Potential HIV Vaccine Adjuvants That Act through Stimulation of CD1d-Restricted natural Killer T Cells
M Poles1,2, A Horowitz1, D Wu3, G W Xing3, Y Kinjo4, B Sullivan4, O Plettenburg3, M Kronenberg4, C H Wong3, D Ho1, and Moriya Tsuji*1,2
1Aaron Diamond AIDS Res Ctr, Rockefeller Univ, New York, NY, USA; 2New York Univ Sch of Med, NY, USA; 3The Scripps Res Inst, La Jolla, CA, USA; and 4La Jolla Inst of Allergy and Immunology, San Diego, CA, USA

Background:  Mouse and human natural killer T (NKT) cells constitute a highly conserved lymphocyte subpopulation that appears to play a role in protection against viral pathogens. The CD1 family of proteins binds self and foreign glycolipids, whose presentation to CD1-restricted T cells results in vigorous cytokine secretion. The nature of these glycolipids is poorly understood.

Methods:  We tested synthesized bacteria-derived glycosphingolipids (GSLs) from Sphingomonas wittichii and sulfatide analogs for their ability to stimulate murine and human NKT cells in vitro. IL-2 production by murine NKT hybridoma cells expressing Va14 was assessed by co-culturing these cells with A20 murine B-cell lines transfected with murine CD1d cDNA (A20mCD1d) in the presence of each glycolipid compound, by ELISA. IFN-g and IL-4 secretion by a human Va24+ NKT cell line was determined by ELISA after co-culture with irradiated Hela cells transfected with human CD1d (Hela-hCD1d) in the presence of each glycolipid compound.

Results:  The two a-galacturonosyl ceramides derived from Sphingomonas wittichii, and the sulfatide analog, while structurally similar to the potent NKT cell agonist a-GalCer, have significant differences in their sugar head group and ceramide portions. Still, the Sphingomonas GSLs and sulfatide analogs are capable of activating murine and human NKT cells as measured by IL-2, and IFN-γ and IL-4 secretion, respectively. To test glycolipid antigen reactivity at the single-cell level in murine Va14 and human Va24 NKT cells, we stained murine NKT hybridoma cells and human NKT cell lines with murine and human CD1d dimers loaded with the glycolipid compounds. Each glycoplid-loaded dimer nearly universally stained the murine and human NKT cells.

Results:  Thus, murine and human NKT cells react to these glycolipids in a fashion comparable to a-GalCer. Since a-GalCer has been shown to enhance the efficacy of HIV vaccines in a murine model, it is likely that these novel glycolipids may also have adjuvant activity and will improve the immunogenicity of existing HIV vaccines.

Keywords: adjuvant; glycolipid; natural killer T cell