Modified antigens in the treatment of allergic disease.

In summary, effects at improvement upon conventional immunotherapy by antigen modification have taken three major directions. First, methods designed primarily to impede allergen release from the site of deposition have been only modestly successful. An example is alum-precipitated extracts which require somewhat fewer injections. Second, attempts to suppress specific IgE production have been unsuccessful in human trials, although antigen-specific IgG levels have increased in a manner similar to that produced by conventional allergen immunotherapy. The third major avenue of antigen modification, to reduce allergenicity while retaining immunogenicity, appears, at present, to be the most promising. Clinical studies of polymerized allergens summarized above have shown that patients can be given a course of polymerized allergen immunotherapy in a few weeks, while a course involving a comparable quantity of unmodified allergen would require years. With the use of polymerized pollen extracts, degree of symptom reduction, persistence of benefit, and magnitude of IgG-blocking antibody induction are comparable to that achieved with unmodified allergens, while the incidence of systemic reactions is greatly reduced. The development of polymerized allergens appears to represent a significant advance which may be expected to expand the clinical utility of allergen immunotherapy.