1. Animals showing natural bacterial allergy to filtrates of B. lepisepticum survive infection by this organism more frequently than weak reactors. This increased resistance is manifested by better localization of infection.
2. Bacterial filtrates injected into skin 24 hours before infection exert a non-specific protection of that area against the organism, even in susceptible animals. The cells of this protected area seldom undergo necrosis when infected.
3. Severe injury of tissues either by chemicals or an antigen-antibody reaction produces a loss of local resistance even in immune animals. Mild injuries have the opposite effect. It is believed that in cases of severe injury, the affected areas undergo a segregation from the circulating antibodies.
4. When bacterial immune serum is injected with a protein antigen into the skin of a sensitized animal, a local alteration occurs in which substances necessary for the effective action of the immune serum are destroyed.
5. A protective action is restored to the altered immune serum by addition of complement to the lesion.
6. It is felt that allergy is not the chief mechanism in cellular resistance to infection, however data are advanced which suggest that allergy does exert local protection by acceleration of the immune processes and by rendering the cells locally refractory to further injury.
7. Chronic infection by a single strain of organism excites cellular reactivity to many strains of bacteria often unrelated biologically. Hence a non-specific mechanism for localizing infections throughout the body may be induced.