INKT cell stimulation by glycolipid ligands modified from α-galactosylceramide results in differential interleukin-2 secretion profiles

Abstract

Abstract Invariant natural killer T (iNKT) cells are a specialized group of unconventional T cells that recognize glycolipids presented by the surface protein CD1d, expressed by most antigen-presenting cells. This results in the rapid secretion of a wide array of cytokines without the need for prior antigen immunization, thus making iNKT cells an attractive target for immunotherapy. Marine sponge sphingolipid α-galactosylceramide (α-GalCer) is a potent agonist for iNKT cell activation, characterized for inducing both Th1- and Th2-like cytokine secretion profiles. There is an increasing interest for the development of Th1- and Th2-polarizing ligands for more focused immunotherapeutic applications. Our aim is to evaluate the iNKT cell activation ability of C6” modified α-GalCer derivatives. We generated and isolated clones from iNKT cell hybridomas derived from a partially humanized mouse, consisting of a knock-in of the human CD1d gene. We selected by flow cytometry iNKT cell populations reactive to α-GalCer presented in the context of the human CD1d molecule. Additionally, we evaluated activation of iNKT cells by C6” modified α-GalCer derivatives and obtained a diverse interleukin-2 response depending on the structural modifications of the ligands and the individuality of the iNKT cell clones. In several cases, this response was more potent than that induced by stimulation with α-GalCer. Our results highlight differences between mouse and human lipid antigen presentation, as well as differences in the magnitude of the cytokine response amongst clonal populations. Our ongoing work aims to elucidate the mechanism for this observation by performing Next Generation Sequencing of the TCR chains of the responding clones.