A Study of the Anaphylactic Mast‐Cell Reaction in vivo Following Desensitization of Sensitized Guinea Pigs

The sensitivity of mast cells to antigen was studied quantitatively in the nasal mucosa of sensitized guinea pigs under pentobarbital anaesthesia. The typical anaphylactic mast‐cell “disappearance”, provoked by i. a. challenge injections of the antigen, could be inhibited with preceding S.C. antigen injections. This desensitization of mast cells was found to have developed within 1 hour following an appropriate S.C. injection and to last for about 2 weeks. Its effectiveness was proportional to the size of the preceding dose of the antigen. The desensitization was never absolute, since high challenge doses could still produce some degree of mast‐cell disappearance. Injections of antigen during the period of sensitization postponed the development of mast‐cell sensitivity to the antigen. Weekly injections of the antigen could maintain the desensitized state. Desensitization with one antigen (egg albumin) did not influence the sensitivity of the mast cells to another antigen (horse serum) and vice versa in double‐sensitized animals. In all experiments the inhibition of mast‐cell reactivity to antigen corresponded to an inhibition of the general anaphylactic symptoms.