Immunotherapy in Atopic Allergy – Antibody Titres and Avidities during Hyposensitization with Birch and Timothy Pollen Allergens

Abstract

The quantities and the avidities of antibodies against birch pollen and, in some sera, timothy pollen were studied in atopic patients during the course of hyposensitization therapy with aqueous or Allyral allergen extracts. The ammonium-sulphate precipitation (ASP) technique was used to determine the allergen-binding capacity of the sera before and after absorption with anti-human IgE antibodies conjugated to Sepharose. Furthermore, IgE antibodies were determined with the radioallergosorbent test (RAST). IgE as well as non-IgE antibody titres increased after initiation of immunotherapy but after 2–3 years of treatment the IgE antibodies decreased, according to RAST results. No consistent pattern of increase or decrease of antibody titres was seen during the pollen seasons. However, a decrease of RAST values as well as of non-IgE titres determined with the ASP technique was found between the post-season sera from the first year of therapy and the pre-season sera the following year in respect of birch pollen allergen. No significant changes of antibody avidities were seen, nor could any significant correlations be found between the patients symptom scores during the birch pollen season and the antibody titres or avidities. The findings were similar for timothy pollen. It is concluded that the improvement of reagin-mediated symptoms found during immunotherapy is not caused by changes in the amounts or avidities of the specific antibodies detectable in the serum with the methods mployed, but other factors have to be sought.