CD244 and listeriosis: However, a recent study using Slamf4−/− mice showed that 2B4 expression drove a stronger protective immune response to oral Citrobacter and Listeria infections, and this correlated with reduced cytokine production from Slamf4−/− T-IEL compared with WT T-IEL in vivo.113 These two studies are yet to be reconciled, although it should be pointed out that the earlier study mainly relied on anti-CD3 stimulation, a non-physiological stimulus.