Delayed Hypersensitivity and Arthus Reactivity in Relation to Host Resistance in Salmonella-Infected Mice

Abstract

Mice vaccinated with living S. enteritidis or S. gallinarum but not with S. pullorum showed a typical delayed-type hypersensitive reaction when injected in the footpad with a protein-containing fraction obtained from cultures of the three strains. Mice immunized with killed suspensions of the three strains developed Arthus but not delayed sensitivity. The active material in the cell-free culture medium was partially purified by chromatography and high speed centrifugation. Delayed reactivity was transferable to normal mice by spleen cells but not by the serum obtained from mice vaccinated with living S. gallinarum. A close temporal relationship was formed between the development of delayed hypersensitivity and the emergence of effective antibacterial immunity. Arthus sensitivity showed no such correlation. S. pullorum whether given as a single dose of living organisms or repeatedly as daily intravenous injections, failed to induce a state of delayed hypersensitivity or any demonstrable antibacterial immunity to an intravenously-injected challenge by S. enteritidis. However, this organism contained an antigen that elicited delayed reaction in mice immunized with S. enteritidis or S. gallinarum. The significance of this observation is discussed.