IL17A and listeriosis: To explore the influence of CYLD on cytokine production in listeriosis, serum cytokine levels were determined at day 5 p.i. Levels of IL-6 and IFN-γ were significantly increased in Cyld−/− mice, whereas serum levels of IL-2, IL-4, IL-10, IL-17, and TNF did not differ between the two mouse strains (Fig. 2A).