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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]

Peritoneal exudate lymphocytes (PEL) of guinea-pigs injected with Freund's complete adjuvant (FCA) were capable of liberating skin reactive factor (SRF) and macrophage migration-inhibitory factor (MIF) when cultured for 24 hours in the presence of sheep red cells (SRC) preincubated with lymph node cells (LNC) of guinea-pigs immunized with SRC in FCA. Similar release of soluble mediators was found in the following situations: (a) incubation of non-immune PEL with SRC sensitized with the exclusion peak of Sephadex G-200 fractionated immune LNC supernatant; (b) incubation of non-immune LNC with complexes of SRC and anti-SRC IgG, prepared from serum of animals immunized with SRC in CFA, and (c) incubation of non-immune LNC with a mixture of SRc urea extract and anti-SRC IgG. SRC incubated for 24 hours with immune LNC and freed of lymphocytes by selective filtration through a Millipore filter, were able to provoke an inflammatory reaction in the skin of normal guinea-pigs, which was delayed in character. These findings are interpreted as suggestive evidence for the non-identity of the mediator-producing and antigen-reactive cells and as support for the hypothesis that a complex composed of antigen and an antibody-like material, secreted by stimulated antigen-reactive lymphocutes, is responsible for the release of soluble mediators in cell-mediated immune reactions. [ABSTRACT FROM AUTHOR]

Albino guinea-pigs were actively sensitized with complete Freund's adjuvant. Tuberculin skin reactivity and tuberculin-induced in vitro mitotic responsiveness of circulating lymphocytes were determined sequentially in each animal after sensitization. In nine of ten animals studied, both skin reactivity and in vitro mitotic response to tuberculin appeared 3 weeks after sensitization. [ABSTRACT FROM AUTHOR]

Guinea-pigs were immunized by injections of blood group substance with incomplete adjuvant, followed after an interval of approximately 2 weeks, by intracutaneous immunization with the same antigen and Freund's adjuvant containing M. tuberculosis. This treatment inhibited the appearance of delayed skin reactions, while circulating antibody production took place as in controls which had received complete adjuvant only with blood group substance, and had delayed skin reactions. The inhibition of the skin reaction was found to be antigen-specific with regard to unrelated antigens, but showed cross-inhibition for serologically different human blood group substances. The first immunization had to be given more than 2 days before the immunization with complete adjuvant. A similar phenomenon was seen with ovalbumin as antigen. In addition to inhibition of the delayed skin reaction, there appeared to be less γ2-antibody to ovalbumin than in ovalbumin plus complete adjuvant-only controls. Passive administration of antibody did not affect the development of a delayed hypersensitivity state in complete adjuvant-immunized animals with blood group substance or ovalbumin as antigen. Present evidence favours an explanation of the phenomenon in terms of temporary paralysis on the part of some of the antibody-producing cells—viz. those concerned with delayed hypersensitivity and γ2-antibody production. [ABSTRACT FROM AUTHOR]