Immunotherapy with monomethoxypolyethylene glycol modified allergens

Abstract

On the basis of the results of experiments in naive mice, i.e., in mice which had not been presensitized, it was anticipated that mPEG-modified allergens would suppress the specific IgE response in allergic humans. However, only minor or no suppression of IgE antibodies was induced on administration of mPEG conjugates in allergic patients with a longstanding IgE response. This observation was later confirmed in pre-sensitized animals. The mPEG-modified allergens can be synthesized in a reproducible manner. This makes mPEG-modified allergens suitable for production and quality control. There is indirect evidence, i.e., identification of IgE and IgG antibody stimulation against all identified allergens, that the relevant determinants are available for processing by the immune system. By contrast, the polymerization of allergens by formaldehyde or glutaraldehyde leads to ill-defined, cross-linked high molecular weight materials. As in the case of other modified allergens, mPEG-modified allergens have been developed primarily because of their lower allergenicity than the original allergen preparations. However, they also retain clinical efficacy of the same magnitude as that induced by unmodified allergen preparations, which is a prerequisite for clinical use. IT with mPEG-modified pollen allergen preparations has been proven to be as effective as IT with unmodified allergens, when these preparations are given in similar doses. Furthermore, a more pronounced beneficial effect can be obtained with higher doses of mPEG-modified allergen, without the risk of side effects which are often precipitated by unmodified allergens. Therefore, it seems reasonable to suggest that children and young adults with developing sensitivity to perennial allergens, and without chronic changes of the bronchial mucosa, are the most suitable candidates for IT with mPEG-modified allergen preparations. Mite asthma, which always includes bronchial inflammation and nonspecific hyperresponsiveness, represents a more complicated model. In mite asthmatics mPEG-modified mite allergen preparations were safer than the corresponding unmodified preparation. Although bronchial sensitivity to allergen and histamine did not change significantly in mite asthmatics during the observation time, it appears that IT with mPEG-modified mite allergen led to a decrease in the releasability of histamine from skin mast cells, as measured by SPT, to a similar degree as observed in pollinosis patients. Therefore, it may be inferred that the allergic component of asthma might be influenced by IT with mPEG allergens. As a consequence, before the start of IT, the degree of reversibility of pathophysiological changes in the bronchial wall should be considered.(ABSTRACT TRUNCATED AT 400 WORDS)