Pathophysiologic mechanisms of allergic and pseudo-allergic reactions to foods, food additives and drugs.

Allergic or pseudo-allergic reactions elicited by per os intake of foods, food additives or drugs may be based on one or several of the following immunopathologic mechanisms: 1) specific IgE bound to mast cells and/or basophils; 2) antigen-IgE soluble complexes hitting various target cells; 3) antigen-IgG complexes generating anaphylatoxins; 4) generation of anaphylatoxins by alternate pathway complement activation; 5) release of mast cell mediators by other direct triggering mechanisms (e.g., basic peptides, peptones); 6) effects on other target cells such as neutrophils and platelets; 7) reactions mediated by specific effector lymphocytes. While allergic reactions in a classical sense involve a sensitization process leading to the formation of specific immunologic agents such as antibodies or specific T lymphocytes, pseudo-allergic reactions appear to involve the same inflammatory mediators which are formed and/or released through different mechanisms and without the necessity for specific sensitization. The complexity of the phenomena possibly involved continues to create great difficulties in the objective diagnosis of food allergy.