Changes in challenge tests following hyposensitization with mite extract

Abstract

Summary The changes in a wide variety of in vivo and in vitro tests following a long course of low antigen dosage hyposensitization therapy in fifteen asthmatic patients with house dust mite allergy are reported. Evidence of clinical improvement was shown by decreased bronchodilator requirement. Bronchial challenge testing showed a significant increase in bronchial tolerance to mite antigen. Nasal and skin tests with mite extract, however, did not show a significant change. In contrast to the development of bronchial tolerance and to the clinical improvement, some of the in vitro tests seemed to provide evidence of hypersensitization. The leucocyte test, for example, showed increased sensitization to the mite antigen, as well as an increase in histamine release by anti‐IgE serum. Total serum IgE was also increased, but this was apparently due to non‐allergen specific IgE. Although the leucocyte test showed increased sensitization to mite antigen, serum reaginic activity as measured by the passive sensitization of human lung did not show any increase. Thus, there seemed to be a difference in the affinity of allergen‐specific IgE for leucocytes as compared with lung tissue. It also appeared that leucocyte response to antigen bore no relationship to sensitization of other tissues, particularly the bronchial tree. The mechanism of clinical hyposensitization by low dosage immunotherapy is discussed. It is suggested that apart from the development of blocking antibodies, other mechanisms seem likely. Among these are a change in the affinity of IgE antibodies for different tissues, and a competition between non‐specific IgE (produced in excess as a result of immunotherapy) and allergen‐specific IgE.

Study of prolonged hyposensitization with D. pteronyssinus extract in allergic rhinitis

“…There has already been evidence from studies of hyposensitization for asthma that, in order to be effective, prolonged treatment of the kind used in the maintenance course in this study is required (Aas, 197! ;Assem & McAllen, 1973). This was borne out in the present study for rhinitis so far as symptomatic improvement was concerned.…”

“…It has been suggested that the patients with a single allergy to DP, as shown by a positive skin test to D. pteronyssinus only, are more likely to obtain benefit from hyposensitization with DP (Smith, 1971;Assem & McAllen, 1973;Choovoravech, 1974). Unfortunately, in the present study, there were only three such patients who completed the maintenance course, so this point could not be investigated.…”

Antibody Response following Prolonged Hyposensitization with <i>Dermatophagoides pteronyssinus</i> Extract

“…A second alternative is that hyposensitization acts on mast cells and they become less responsive to antigen. In some ragweed allergic patients improve ments in symptoms have been associated with decreased histamine release from circu lating basophils [14,24], However, no con sistent evidence of this kind has been ob tained for the house dust mite [8,9].…”

IgG2 Antibodies Block IgE Antibody-Induced Asthma in Guinea Pigs

“…Zeiss et al [4] reported that IgG antibody levels/IgE antibody levels ratio increased in patients treated with antigen E. This ratio was related significantly to symptom scores. Assem and McAllen [5] reported that thresholds of allergens in provoca tion tests increased after immunotherapy in miteasthmatic patients, and D'Souza et al [6] showed that precipitating antibodies to mite increased when deter mined by radioimmunelectrophoresis. Although it was shown [2] that IgG-blocking antibodies to rag weed blocked in vitro histamine release from patient leukocytes, there has been no crucial evidence that IgG-blocking antibodies prevent IgE antibody-in duced asthma at inhalation of allergens.…”