Studies on passive cutaneous anaphylaxis in the rat with disodium cromoglycate. II. A comparison of the rat anti-dnp 7S 2 and rat reagin induced cutaneous reactions.

A study of the passive cutaneous anaphylactic reaction induced by anti-DNP 7Sγ2 antibodies was undertaken in rats to compare this anaphylactic reaction with that induced by rat reagin. This study revealed that disodium cromoglycate was capable of inhibiting the 7Sγ2 induced PCA reaction immediately following antigen challenge but not the slow developing late reaction. Using various doses of disodium cromoglycate on a series of rat reagin PCA reactions and on a series of early 7Sγ2 induced PCA reactions, similarities in dose dependence were demonstrated suggesting that certain pathways might be common to both reactions. Studies using 48/80 treatment after sensitization revealed inhibition of both early and late 7Sγ2 reactions. Concomitant sensitization with rat reagin and 7Sγ2 at various concentrations demonstrated that either antibody was capable of inhibiting the reaction induced by the other antibody, suggesting similar sensitization sites might be involved. In actively sensitized rats with a high reagin titre we were unable to induce a 7Sγ2 or rat reagin PCA reaction whereas a cutaneous reaction of the `Arthus' type was readily induced. It is concluded that passive sensitization by anti-DNP 7Sγ2 antibodies has certain factors in common with sensitization by rat reagin and that the sensitized mast cell plays a vital role in the elicitation of both early and late 7Sγ2 PCA reactions.