Structure-Function Implications of the Ability of Monoclonal Antibodies Against alpha-Galactosylceramide-CD1d Complex to Recognize beta-Mannosylceramide Presentation by CD1d

• iNKT cells are CD1d-restricted T cells recognizing lipid antigens. The prototypic iNKT cell-agonist alpha-galactosylceramide (alpha-GalCer) alongside compounds with similar structures induces robust proliferation and cytokine production of iNKT cells and protects against cancer in vivo. Monoclonal antibodies (mAbs) that detect CD1d-alpha-GalCer complexes have provided critical information for understanding of antigen presentation of iNKT cell agonists. Although most iNKT cell agonists with antitumor properties are alpha-linked glycosphingolipids that can be detected by anti-CD1d-alpha-GalCer mAbs, beta-ManCer, a glycolipid with a beta-linkage, induces strong antitumor immunity via mechanisms distinct from those of alpha-GalCer. In this study, we unexpectedly discovered that anti-CD1d-alpha-GalCer mAbs directly recognized beta-ManCer-CD1d complexes and could inhibit beta-ManCer stimulation of iNKT cells. The binding of anti-CD1d-alpha-GalCer mAb with beta-ManCer-CD1d complexes was also confirmed by plasmon resonance and could not be explained by alpha-anomer contamination. The binding of anti-CD1d-alpha-GalCer mAb was also observed with CD1d loaded with another beta-linked glycosylceramide, beta-GalCer (C26:0). Detection with anti-CD1d-alpha-GalCer mAbs indicates that the interface of the beta-ManCer-CD1d complex exposed to the iNKT cell TCR can assume a structure like that of CD1d-alpha-GalCer, despite its disparate carbohydrate structure. These results suggest that certain beta-linked monoglycosylceramides can assume a structural display similar to that of CD1d-alpha-GalCer and that the data based on anti-CD1d-alpha-GalCer binding should be interpreted with caution.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Immunologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Immunology in the medical area (hsv//eng)

Nyckelord

natural killer T cells

CD1d

beta-mannosylceramide

alpha-galactosylceramide

L363

t-cell-receptor

nkt cells

tumor-immunity

crystal-structure

in-vivo

activation

stimulation

antigens

ligands

zeta

Immunology

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