TNF-α, however, is just one of the cytokines released in response to L. monocytogenes with other pro-inflammatory cytokines, including IL-6 and IL-1β, released during infection in vivo[7], [8], and mast cells have been shown to secrete these in response to L. monocytogenes in vitro[7], [9], [10]. This evidence concerns the gene IL1B and infection.