To investigate whether TLR4-mediated differential production of IL-4 and IFN-γ by iNKT cells regulates iNKT cell-mediated immune diseases, we compared joint inflammation in CD1d−/− mice adoptively transferred with either WT or TLR4-deficient iNKT cells in the K/BxN serum transfer model. This evidence concerns the gene IFNG and immune system disorder.