 Tyk2−/− mice displayed a lack of responsiveness to a small amount of IFN-α, but they respond normally to a high concentration of IFN-α/β.In addition, these mice respond normally to IL-6 and IL-10, suggesting that Tyk2 is dispensable for mediating for IL-6 and IL-10 signaling and does not play a major role in IFN-α signaling.Although Tyk2−/− mice are phenotypically normal, they exhibit abnormal responses to inflammatory challenges in a variety of cells isolated from Tyk2−/− mice.