Identification of novel glycolipid ligands activating a sulfatide‐reactive, CD1d‐restricted, type II natural killer T lymphocyte

Abstract

Sulfatide-reactive CD1d-restricted natural killer T (NKT) lymphocytes belong to the type II NKT cell subset with diverse TCRs, and have been found to regulate experimental autoimmune encephalomyelitis, tumor immunity, and experimental hepatitis in murine models. NKT cells can be activated by self-lipids presented by CD1d, manifested as autoreactivity. The identity of most of these self-lipids remains unknown. By isolating lipids from a CD1d-expressing, highly stimulatory antigen presenting cell, we identified isoforms of β-glucosylceramide (GlcCer), with sphingosine and fatty acid chain lengths of C24:0 and C16:0, that activated a sulfatide-reactive type II NKT cell hybridoma. A screen of structurally related glycosphingolipids demonstrated β-galactosylceramide (GalCer) as another ligand, and further, that the lysoforms were the most potent isoform of the glycosphingolipid ligands, followed by isoforms with a long fatty acid chain of C24. Thus, the same type II NKT cell was activated by several ligands, namely sulfatide, GlcCer, and GalCer. However, CD1d-dependent reactivity to antigen presenting cells lacking all GlcCer-based glycosphingolipids, or all glycosphingolipids, was maintained. This suggests that other endogenous, nonglycosphingolipid, lipid ligands contribute to steady-state autoreactivity by type II NKT cells. antigen presenting molecule CD1d, expressed predominantly by hematopoietic cells. Upon activation, NKT cells display innatelike features such as rapid production of large amounts of both inflammatory and anti-inflammatory cytokines, including IFN-γ and IL-4, and they enhance DC maturation. Through these features, they are important in the initiation of innate immunity and also in the direction and regulation of the adaptive immune response resulting in the modulation C 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.eji-journal.eu 2852 Sara Rhost et al. Eur. J. Immunol. 2012. 42: 2851-2860 of tumor immunity, autoimmunity, and microbial infections [1][2][3]. NKT cells can be activated both by microbial and endogenous lipids. The latter may be upregulated in antigen presenting cells (APCs) upon their activation, or be derived from other cells of the body and presented by APCs [4][5][6]. Sulfatide was among the first self-glycosphingolipids demonstrated to stimulate T lymphocytes [7]. Sulfatide is found in large amounts in the central nervous system, mainly located in the myelin, a target of the autoimmune process during multiple sclerosis. Indeed, the frequencies of sulfatide-reactive T cells were increased in multiple sclerosis patients [7], and sulfatide-reactive CD1d-restricted NKT cells accumulated in the CNS of mice during experimental autoimmune encephalomyelitis [8], a model for the human disease, suggesting that the cells were engaged in the disease process. This notion was supported by studies showing that sulfatide injection protected CD1d-sufficient mice from the disease, consistent with the hypothesis that that sulfatide-reactive NKT cells could suppress the autoimmune process ...

Polyclonal type II natural killer T cells require PLZF and SAP for their development and contribute to CpG-mediated antitumor response

“…Previous studies with type II NKT cell hybridomas have identified several self-lipid antigens recognized by type II NKT cells, including phospholipids, β-GlcCer, and sulfatide (27,(36)(37)(38)(39)(40). Interestingly, we found that 4get + type II NKT cells are potently activated by β-GlcCer containing C12:0 and C24:1 acyl chains, suggesting that a significant proportion of type II NKT cells recognize β-GlcCer.…”

Recognition of microbial and mammalian phospholipid antigens by NKT cells with diverse TCRs

“…Indeed, dNKT cells do not recognize α-GalCer or any of the α-glycan-linked microbial lipid antigens that are recognized by iNKT cells, and the selflipid sulfatide, which is recognized by a small subset of mouse dNKT cells, is not recognized by iNKT cells (9,10). Furthermore, the self-antigen β-GluCer, which stimulates most or all human and mouse iNKT cells, stimulates only a small subset of mouse dNKT cells (11,12). A number of studies have documented, or inferred, a function for dNKT cells during infection (13,14), yet the antigens that stimulate dNKT cells during infection remain unknown.…”

Recent advances in food allergy

“…Food Technol., Campinas, v. 19, e2016047, 2016 Recent advances in food allergy Alcocer, M. J. C. et al cell CAUBET et al, 2014). The majority of NKT cells express highly restricted TCRs with an invariant α-chain (Vα24-Jα18 in humans and Vα14-Jα18 in mice) and limited β-chains, therefore they are referred to as Type I or invariant NKT cells (iNKT) (PEI et al, 2011;RHOST et al, 2012). Type II cells form the remaining NKT cells and express non-invariant TCRs.…”