The eosinophil response to toxoids and its inhibition by antitoxin.

E OSINOPHIL GRANULOCYTES are a conspicuous cellular component of inflammatory exudates, local granulomatous reactions, and regional lymphatic tissues.15 Although they have been commonly observed and frequently studied in blood and in areas of chronic allergic reactions, parasitic infestations, repeated exposure to foreign protein, metastasizing tumors, and homograft rejection, the physiologic significance of these cells is still unknown. At least 3 possible mechanisms for their local accumulation have been proposed: 1. Eosinophilotactic factors are released by the complexing of antigen and antibody#{176}8 and the responding eosinophils presumably engulf these complexes.#{176}1’ 2. Fibrin formation or large molecular aggregates may induce a local accumulation of eosinophils and the activated profibrinolysins or similar enzymes in eosinophils play a part in the dissolution of the aggregates.1213 3. Exposure to antigen induces a reaction in specific antigen-sensitive mononuclear cells which release eosinophilotactic substances. Eosinophils play a role in cellular breakdown and they presumably could bring about transfer of material from one cell to another during these reactions.16’17 Although many reviewers over the past 10 years have favored the chemotactic attraction of eosinophils to antigen-antibody complexes as a possible explanation for blood and tissue eosinophilias, it has been repeatedly shown that not every antigen-antibody reaction is accompanied by an eosinophilia.2”8’1#{176} In our laboratory we were unable to demonstrate a local accumulation of eosinophils following an injection of antigen into passively immunized animals.2#{176} Furthermore, in animals sensitized with multiple injections of antigen, there was an inverse relationship between humoral antibody titers at the time of challenge and the subsequent eosinophil response.21 It seemed, therefore, advisable to determine the effects of humoral antibody injected into animals primed to give high eosinophil responses. The experiments described in this report are concerned with the effects of heterologous and isologous antitoxin administered prior to or following an injection of tetanus toxoid into immunized mice. The results indicate that the presence of specific antibody has little or no inhibiting effect upon an initial eosinophilia which occurs within 24 hours after injection of antigen. On the