Fig. (2) Salmonella-infected macrophages augment IFN-γ production by antigen-stimulated DO11.10 CD4+ T cells. Peritoneal macrophages were isolated and cultured in the presence of medium alone or viable Salmonella. Following exposure for 45 minutes, cells were washed to remove any extracellular bacteria with gentamicin-containing medium. Magnetically separated DO11.10 CD4 + T cells, B cells, and OVA peptide were added as indicated (A). In other studies, bone marrow-derived dendritic cells were infected with Salmonella and treated with gentamicin 45 minutes post-infection and prior to addition of DO11.10 CD4 + T cells, B cells, and OVA peptide (B). Levels of IFN-γ were measured by enzyme immunoassay, and are reported as mean values of triplicate determinations. These studies were performed three times with similar results.