Abstract
Effector responses of cell-mediated immunity were studied in mice immediately and 3 months after immunisation with different kinds of salmonella vaccine. Whereas immunisation with live Salmonella enteritidis generated delayed hypersensitivity and activated macrophages, immunisation with formalised vaccine generated neither. Although activated macrophages had declined considerably by 3 months after immunisation, the delayed-hypersensitivity response had persisted. It was possible to generate activated macrophages in these mice by stimulation with sonicate antigens of the immunising strain or Salmonella paratyphic C. Delayed-hypersensitivity responses were elicited in mice, immunised with live S. enteritidis, by sonicate antigens of the homologous strains, S. gallinarum or S. paratyphi C.