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The effectiveness of antigen aerosol-induced desensitization has been investigated in guinea-pigs actively sensitized with antigen, alone or incorporated in Freund's adjuvants. Rates of desensitization, and the ability of animals to regain anaphylactic hypersensitivity following intensive desensitization, have been considered in terms of relative rates of antibody production, levels of circulating antibody, and qualitative differences in the antibody produced. A protective component observed during desensitization in adjuvant-treated animals is considered to be a property both of high levels of circulating antibody and of the presence of certain non-specific factors which interfere with the sensitization process. [ABSTRACT FROM AUTHOR]

Anaphylactic hypersensitivity of isolated guinea-pig ileum preparations has been evaluated by investigation of antigen-dose/response relationships, in vitro. The influence of Freund's adjuvants on active sensitization has been investigated. In contrast to the inhibitory influence previously observed in vivo, the degree of hypersensitivity of isolated tissues in vitro was potentiated by the adjuvants. It is thought that high circulating titres of antibody in vivo exerted a protective or neutralizing effect in relation to challenging doses of antigen. Isolated tissues were freed from this influence. Tissues sensitized with the aid of Freund's complete adjuvant (FCA) revealed the influence of other inhibitory mechanisms, due probably to interaction of various antibody types. [ABSTRACT FROM AUTHOR]