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Updated: Oct 23, 2025
Interview: Glycolipid Antigen Presentation by CD1d and the Therapeutic Potential of NKT cell Activation
Published on: December 31, 2007
Benzofuran sulfonates and small self-lipid antigens activate type II NKT cells via CD1d
Catarina F Almeida1,2, Dylan G M Smith3,4, Tan-Yun Cheng5
1Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC 3000, Australia; cdos@unimelb.edu.au bmoody@bwh.harvard.edu sjwill@unimelb.edu.au dan.pellicci@mcri.edu.au godfrey@unimelb.edu.au.
Abstract:
Natural killer T (NKT) cells detect lipids presented by CD1d. Most studies focus on type I NKT cells that express semi-invariant αβ T cell receptors (TCR) and recognize α-galactosylceramides. However, CD1d also presents structurally distinct lipids to NKT cells expressing diverse TCRs (type II NKT cells), but our knowledge of the antigens for type II NKT cells is limited. An early study identified a nonlipidic NKT cell agonist, phenyl pentamethyldihydrobenzofuransulfonate (PPBF), which is notable for its similarity to common sulfa drugs, but its mechanism of NKT cell activation remained unknown. Here, we demonstrate that a range of pentamethylbenzofuransulfonates (PBFs), including PPBF, activate polyclonal type II NKT cells from human donors. Whereas these sulfa drug-like molecules might have acted pharmacologically on cells, here we demonstrate direct contact between TCRs and PBF-treated CD1d complexes. Further, PBF-treated CD1d tetramers identified type II NKT cell populations expressing αβTCRs and γδTCRs, including those with variable and joining region gene usage (TRAV12-1-TRAJ6) that was conserved across donors. By trapping a CD1d-type II NKT TCR complex for direct mass-spectrometric analysis, we detected molecules that allow the binding of CD1d to TCRs, finding that both selected PBF family members and short-chain sphingomyelin lipids are present in these complexes. Furthermore, the combination of PPBF and short-chain sphingomyelin enhances CD1d tetramer staining of PPBF-reactive T cell lines over either molecule alone. This study demonstrates that nonlipidic small molecules, which resemble sulfa drugs implicated in systemic hypersensitivity and drug allergy reactions, are targeted by a polyclonal population of type II NKT cells in a CD1d-restricted manner.
Insights
Non-lipidic molecules, similar to sulfa drugs, activate type II Natural Killer T (NKT) cells by binding to CD1d-TCR complexes. This discovery expands understanding of NKT cell antigen recognition and potential drug allergy mechanisms.
Area of Science:
- Immunology
- T cell biology
- Drug allergy mechanisms
Background:
- Natural Killer T (NKT) cells are crucial immune sentinels, with type I NKT cells recognizing lipid antigens presented by CD1d molecules.
- Type II NKT cells, characterized by diverse T cell receptors (TCRs), also interact with CD1d but their specific antigens remain largely unknown.
- Phenyl pentamethyldihydrobenzofuransulfonate (PPBF), a non-lipidic compound structurally similar to sulfa drugs, was previously identified as an NKT cell agonist, but its activation mechanism was unclear.
Purpose of the Study:
- To investigate the mechanism by which pentamethylbenzofuransulfonates (PBFs), including PPBF, activate type II NKT cells.
- To identify the specific molecular interactions between PBFs, CD1d, and type II NKT cell TCRs.
- To explore the implications of these findings for understanding drug hypersensitivity reactions.
Main Methods:
- Activation assays using polyclonal human type II NKT cells and various PBFs.
- Co-crystallization and mass spectrometry to analyze CD1d-TCR complexes.
- Tetramer staining with CD1d-PBF complexes to identify NKT cell populations.
- Functional assays combining PBFs and short-chain sphingomyelin lipids.
Main Results:
- PBFs, including PPBF, directly activate polyclonal type II NKT cells from human donors.
- Direct physical interaction between TCRs and CD1d-PBF complexes was demonstrated.
- CD1d-PBF tetramers identified type II NKT cells expressing conserved TCR gene segments (TRAV12-1-TRAJ6).
- Mass spectrometry revealed that both PBFs and short-chain sphingomyelin lipids bind to CD1d within NKT TCR complexes.
- Combined PBF and sphingomyelin treatment enhanced NKT cell activation.
Conclusions:
- Non-lipidic small molecules, structurally resembling sulfa drugs, are recognized by type II NKT cells in a CD1d-restricted manner.
- This interaction involves direct TCR engagement with CD1d-PBF complexes, potentially explaining drug-induced hypersensitivity.
- The findings broaden the scope of known CD1d-presented antigens to include non-lipidic compounds and highlight a novel mechanism for NKT cell activation.
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