Detergents alter the stability and lipid binding properties of the CD1d immunoreceptor.

CD1d, a non-classical immunoreceptor, plays a central role in lipid antigen presentation to a variety of T cell types. Despite the widespread use of detergents to measure and manipulate lipid/CD1d interactions in vitro, in situ, and in vivo, the molecular basis by which detergents influence the stability of CD1d and its lipid binding properties remains poorly understood. We evaluated the ability of human CD1d to associate with a panel of 13 structurally and chemically diverse detergents spanning non-ionic, anionic, cationic, and zwitterionic classes. Through conventional intrinsic tryptophan fluorescence binding assays, complemented by the application of microscale thermophoresis and nano differential scanning fluorimetry, we quantified detergent/CD1d binding affinities and evaluated their impact on CD1d thermal stability. In silico modeling with the machine learning-based tool Chai-1 provided plausible detergent binding modes, which mirror docking orientations observed for native lipid ligands within the antigen binding groove. High-affinity detergents were shown to exhibit the capacity to block lipid binding in a lipid-dependent manner, implicating features that modulate access to the CD1d groove. These findings provide mechanistic insights into detergent-mediated modulation of CD1d structure, stability, and function, and offer a quantitative framework for optimizing lipid-loading protocols, detergent extraction approaches, and lipid antigen-based immunological assays.