Fig. 3. Impaired Ag-specific CD4+ T cell response in Sirpα^−/− mice after Salmonella infection.

WT and Sirpα^−/− mice were infected i.v. with 5 × 10⁵ attenuated Salmonella (BRD509) for a total of five weeks. All mice were treated with antibiotics during week 3 and 4. A, Purified splenic CD4+ T cells from infected mice were co-cultured with Salmonella specific CD4 T cell antigen (SseJ, SseI, FliC or PagC) in the presence of irradiated APCs for 20 hrs in ELISPOT plate pre-coated with anti-IFNγ. Antigen-specific CD4 T cell number were determined. Data represents three similar experiments with at least three mice per group. B and C, One million total splenocytes from infected WT and Sirpα^−/− mice were co-cultured with Salmonella specific CD4 T cell antigens (SseJ, SseI, FliC or PagC) for 24-48 hrs. Cytokine productions in culture supernatants were determined by cytokine ELISA. Data represents three similar experiments with at least three mice per group. D and E, One million total splenocytes from infected WT and Sirpα^−/− mice were co-cultured with serial diluted heat-killed Salmonella (HKST) for 24-48 hrs. Cytokine productions in culture supernatants were determined by cytokine ELISA. Data represents three similar experiments with at least three mice per group.