CD28 and infection: In order to further characterise the impact of NF-κB suppression on the host inflammatory response, cytokine production by isolated Peyer's patch and spleen-derived cells was assessed, in vitro, following anti-CD3/CD28 stimulation (lymphocyte response) or LPS stimulation (innate TLR-4 response) immediately prior to S. typhimurium infection (Day 0) or four days (Day 4) after infection.