Depigmented and polymerised house dust mite allergoid: allergen content, induction of IgG4 and clinical response.

BACKGROUND: Polymerised allergenic extracts (allergoids) are commonly used in allergen immunotherapy. Clinical efficacy and safety of these extracts have been demonstrated. Recently, allergen sequences have been identified by mass spectrometry in depigmented and polymerised (Dpg-Pol) extracts. The objectives of this study were to investigate the presence of allergens in Dpg-Pol extracts of house dust mite and to analyze the immunological changes induced by these extracts in asthmatic patients enrolled in a double-blind, placebo-controlled study. METHODS: Dpg-Pol extracts were manufactured and vaccines with a composition of 50% Dermatophagoides pteronyssinus and 50% D. farinae (100 HEPL/ml) were prepared. Allergen composition was analyzed by mass spectrometry. Patients with asthma and rhinoconjunctivitis were treated in a 1-year, double-blind, placebo-controlled, parallel-group study with 6 up-dosing and monthly maintenance injections. Specific IgE and IgG4 titres to D. pteronyssinus, Der p 1 and Der p 2 were measured in patients' sera using the CAP system and direct ELISA experiments. RESULTS: Sequences from the major allergens Der p 1 and Der p 2 and from other allergens were identified in native and Dpg-Pol extracts. There was a statistically significant increase in specific IgG4, a decrease in the ratio of IgE/IgG4 to D. pteronyssinus and a significant increase in specific IgG4 to Der p 1 and Der p 2 in the patients allotted to active treatment. CONCLUSIONS: The detection of allergen sequences suggests preservation of major and minor allergens in Dpg-Pol allergoids from house dust mites. Efficacy in asthma treatment and the increase in specific IgG4 seem to be associated with the presence of major allergens in Dpg-Pol allergen extracts.

Clinical cross-reactivity between Artemisia vulgaris and Matricaria chamomilla (chamomile).

Artemisia vulgaris is a common weed and an important source of allergens on the subtropical island of Tenerife, Canary Islands, Spain. It pollinates mainly from July to September, although, due to some local climatic conditions, it may flower throughout the year. Cross-reactivity with hazelnut, kiwi, birch, several Compositae (Ambrosia, Chrysanthemum, Matricaria, Solidago) and grass allergens has been suggested. Few studies have addressed the issue of in vivo cross-reactivity between A. vulgaris and Matricaria chamomilla. The objective of this study was to perform conjunctival and bronchial challenges with A. vulgaris and M. chamomilla and oral challenge with chamomile in 24 patients with asthma and/or rhinitis sensitized primarily to A. vulgaris. Skin prick tests with M. chamomilla were positive in 21 patients. Eighteen patients had a positive conjunctival provocation test with a A. vulgaris pollen extract and 13 patients had a positive conjunctival provocation test with a M. chamomilla pollen extract. Bronchial provocation tests with A. vulgaris were positive in 15 patients and with M. chamomilla pollen in another 16 individuals. Oral provocation tests, conducted with a commercial chamomile infusion were positive in 13 patients. Nine of these individuals were skin test positive to food allergens and 17 to others pollens of the Compositae family. This study confirms a high degree of in vivo cross-reactivity between A. vulgaris and M. chamomilla. Sensitization to A. vulgaris seems to be a primary risk factor for experiencing symptoms after the ingestion of chamomile infusions. Based on the results of bronchial provocation tests, M. chamomilla pollen could be a relevant inhalant allergen.

The capturing of pollens in the atmosphere of La Laguna City, Tenerife, Canary Islands 1990-1995.

This paper forms part of a Doctorate Thesis, carried out in the Allergy and Immunology Department of the Nuestra Señora de la Candelaria Hospital, Tenerife, entitled "Epidemiology of Pollens on the Island of Tenerife. Allergy to Pollen". This paper deals with the capturing of pollen in the atmosphere of the city of La Laguna, Tenerife, during the period 1990-1995, and demonstrates that the Occidental Islands of the Canarian Archipelago are similar to a miniature continent with a special microclimate and a large amount of vegetation, where all classes of pollen can be found given the large variety of plants and trees including native species. High concentrations of more than 50 grains of pollen per m3 can be found in the air of the Occidental Islands, above all wild grasses, cultivated grasses, weeds, Artemisa vulgaris, Parietaria officinalis and Plantago lanceolata, and in a lowe proportion, Cupressaceae, Pinaceas, Mercurialis and Rumex. We have pollen concentrations very similar to other parts of the continent.