However in contrast to TNFα, the expression of IL-33 was significantly enhanced upon infection specifically with live Salmonella. Exposure to live bacteria significantly increased IL-33 production by iSCs, compared with the response to heat-killed bacteria (224.74 ± 42.80 vs. 173.25 ± 32.24 pg/ml, p < 0.01). This evidence concerns the gene IL33 and infection.