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Background: Aluminium-adsorbed six grass pollen allergoid therapy for 2 years was found to be efficacious and safe in patients with hay fever and seasonal asthma. Using high-dose, hypoallergenic allergen products (allergoids) enables a short-term pre-seasonal treatment regimen. However, it is not known whether further treatment beyond 2 yrs had any additional benefit., Methods: Following an initial 2-year randomized, double-blind, multi-centre, placebo-controlled clinical trial in 154 grass pollen-allergic patients, an additional short course of specific immunotherapy with the high-dose, hypoallergenic grass pollen preparation Allergovit was performed in 61 patients of the active treatment group during the 3rd open-label treatment year., Results: Further treatment of patients with the Allergovit 6-grass pollen preparation resulted in a further reduction of symptom medication score and improved quality of life in comparison to the first and second treatment year. Changes in allergen-specific IgG4 levels supported these results., Conclusions: Pre-seasonal short-term immunotherapy with the high-dose, hypoallergenic allergen preparation Allergovit has been shown to be efficacious and safe. A course of three years of 6-grass pollen SIT further improves allergic symptoms, quality of life and reduces the need for anti-allergic medication.

Twenty patients suffering from birch pollen allergy received two or three courses of immunotherapy in successive years. In 9 patients, the fruit allergy improved; 4 patients reported no improvement. In 3 patients, the fruit allergy developed after beginning the immunotherapy. At the end of the 3 years, 16 of these patients were allergic to fruit, 13 of them to apple. After each preseasonal course of immunotherapy with tree pollen extract, a temporal and parallel increase in the titers of IgE antibodies to birch pollen allergens and apple allergens were observed. In contrast, only the titers of birch pollen allergen specific IgG and IgG4 increased, whereas apple allergen specific IgG and IgG4 did not, or only very slightly. In Western blot studies, IgG4 antibodies bound to more components of apple extract than birch pollen extract. On the average, IgG4 antibodies recognize more components of apple and birch pollen extracts than do IgE antibodies. In histamine release studies, the sensitivity of washed leukocytes to birch pollen extract decreased significantly during the observation time. However, the difference between apple extract-induced histamine release before and after immunotherapy was not significant. None of the immunological parameters investigated here correlate well with severity or prognosis of the fruit (apple) allergy. The clinical improvement of pollinosis was associated with a rise in birch pollen specific IgG4 antibody titers and a decrease of allergen-induced histamine liberation. Beside improvement of the fruit allergy in 56% of the cases, the courses of apple specific IgE and IgG4 antibody titers seem to indicate a slight sensitization against apple allergens.

Forty patients with tree pollen-induced allergy (rhinitis, conjunctivitis or combination from both with asthma) were hyposensitized with an extract from isolated birch pollen or a pollen mixture (hazel-, alder-, oak- and hornbeam pollen). The distribution of the different extracts was random. After 3-year treatment, no statistical differences were found between the two groups, especially regarding clinical effectiveness, duration of symptoms or symptom score. In conclusion, we recommend a hyposensitization with birch pollen extract in tree pollen-induced allergy. If evidence is present of sensitization against other tree pollens, especially hazel or alder, or in cases without therapeutic effect after two years of hyposensitization with birch pollen, an attempt with a tree pollen mixture extract is indicated.