Possible role of IgE-mediated reaction in immunity

The effect of a local IgE-mediated hypersensitivity reaction on the neutralization of diphtheria, toxin at skin sites was studied in monkeys passively immunized with human IgG antitoxin. When a mixture of toxin with ragweed allergen was injected intracutaneously into skin sites that had been sensitized with serum from ragweedsensitive patients, the sensitized sites tolerated a significantly greater dose of toxin than did unsensitized sites. An injection of anti-IgE, which induced reversed-type reaginic hypersensitivity reaction, together with the challenging toxin, similarly increased the toxin-neutralizing capacity of the skin sites. In nonimmunized animals, however, IgE-mediated reactions did not show any effect on local resistance. The results indicated that an increased toxin-neutralizing capacity of the local skin sites in passively immunized animals was due to translocation of serum IgG antibody into the skin sites rather than a possible dilution of the toxin by edema fluid. A possible "gatekeeper" role of IgE antibody system in local immunity of mucosal systems was discussed.