Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

CD1d-restricted natural killer T (NKT) cells, expressing the invariant T cell antigen receptor (TCR) chain encoded by Valpha14-Jalpha18 gene segments in mice and Valpha24-Jalpha18 in humans [invariant NKT (iNKT) cells], contribute to immunoregulatory processes, such as tolerance, host defense, and tumor surveillance. iNKT cells are positively selected in the thymus by CD1d molecules expressed by CD4(+)/CD8(+) cortical thymocytes. However, the identity of the endogenous lipid(s) responsible for positive selection of iNKT cells remains unclear. One candidate lipid proposed to play a role in positive selection is isoglobotrihexosylceramide (iGb3). However, no direct evidence for its physiological role has been provided. Therefore, to directly investigate the role of iGb3 in iNKT cell selection, we have generated mice deficient in iGb3 synthase [iGb3S, also known as alpha1-3galactosyltransferase 2 (A3galt2)]. These mice developed, grew, and reproduced normally and exhibited no overt behavioral abnormalities. Consistent with the notion that iGb3 is synthesized only by iGb3S, lack of iGb3 in the dorsal root ganglia of iGb3S-deficient mice (iGb3S(-/-)), as compared with iGb3S(+/-) mice, was confirmed. iGb3S(-/-) mice showed normal numbers of iNKT cells in the thymus, spleen, and liver with selected TCR Vbeta chains identical to controls. Upon administration of alpha-galactosylceramide, activation of iNKT and dendritic cells was similar in iGb3S(-/-) and iGb3S(+/-) mice, as measured by up-regulation of CD69 as well as intracellular IL-4 and IFN-gamma in iNKT cells, up-regulation of CD86 on dendritic cells, and rise in serum concentrations of IL-4, IL-6, IL-10, IL-12p70, IFN-gamma, TNF-alpha, and Ccl2/MCP-1. Our results strongly suggest that iGb3 is unlikely to be an endogenous CD1d lipid ligand determining thymic iNKT selection.

Original publication




Journal article


Proc Natl Acad Sci U S A

Publication Date





5977 - 5982


Animals, Antigens, CD, Antigens, Differentiation, T-Lymphocyte, B7-2 Antigen, Chemokine CCL2, Chromatography, High Pressure Liquid, Galactosyltransferases, Globosides, Heterozygote, Humans, Interferon-gamma, Interleukin-10, Interleukin-12, Interleukin-4, Interleukin-6, Killer Cells, Natural, Lectins, C-Type, Mice, Mice, Knockout, Models, Biological, Tumor Necrosis Factor-alpha, Up-Regulation