CD4 and infection: S. Typhimurium can kill CD8α+ dendritic cells in mesenteric lymph nodes and can inhibit T cell proliferation by a direct, contact-dependent immunosuppressive effect, which inhibits the ability of T cells to produce cytokines and proliferate.123,124 CD4+ T cells specific for Salmonella have been identified shortly following infection; however, they do not play a role in battling the infection until several weeks later and this delay requires Salmonella pathogenicity island-2.