Similar biological activity in skin prick test for Oralair® (8200 BAU) and Grazax® (6200 BAU) reinforces effective SLIT dosing level.

In Europe, allergen extracts are standardized based on skin prick wheal size in 20-30 allergic subjects. To understand the biological activity of clinically effective Sublingual immunotherapy, we used this method to determine the biological activity of solution and tablet Timothy grass pollen (TIM) extracts, compared to an FDA-approved extract (Reference) of 10 000 BAU/ml. Blinded, quadruplicate skin prick tests with concentrate and three serial half-log dilutions allowed the construction of a semilogarithmic regression line per extract. Bioequivalent allergy units (BAU) values were obtained from the comparison with reference. Extracts and dilutions showed a neat linear dose response (all: R2 > 0.98) in 33 rhinitis patients. Relative potencies: Staloral® 12 000 BAU/ml, Soluprick® 10 300 BAU/ml, Oralair® 8200 BAU, and Grazax® 6200 BAU. Even though all extract concentrates differed in wheal size (P = 0.01-0.001), Grazax® producing a 25% smaller wheal size than Oralair® , and the biological activity of these clinically effective TIM tablets led in the same range (6200-8200 BAU; 0.92-1.23 cm2 ). SLIT dose-finding studies for other pollens might start with allergen extracts producing 1.1 cm2 wheal surface.

A comparison of in vitro potency between European and Mexican allergen extracts and US (CBER/FDA) reference extracts.

BACKGROUND: The most important allergen manufacturers are based in Europe and in the US. In some countries local products are also sold. No comparison between European, US and local products has been made until now. AIM OF THE STUDY: To determine total protein content and total specific IgE binding capacity or major allergen content of diagnostic extracts from European, US and Mexican origins relative to the CBER/FDA reference extracts for Dermatophagoides pteronyssinus (Dpt), Bermuda grass and cat (10,000(B) AU/mL). METHODS: Diagnostic extracts were purchased from various manufacturers, blinded and shipped to the analysing laboratory, where the following assays were conducted: total protein concentration (Bradford), specific IgE competition ELISA (Dpt and Bermuda grass) and determination of Fel d 1 U/mL. When available, CBER/FDA recommended tests and reagents were used. RESULTS: Total protein content of US reference extracts was higher than all other extracts. Relative potency of European and US-bought Dpt extracts 3,300-4,400 AU/mL, Bermuda grass 800-2,500 BAU/mL and cat 2.1-4.4 Fel d IU/mL (Ref. 19 U/mL), with one exception. Locally produced Mexican products were almost all below 1,000 (B)AU/mL. CONCLUSIONS: Three diagnostic extracts from European manufacturers and from Mexican providers which obtain extracts in US have a <50% relative potency compared to 10,000 (B)AU/mL US extracts. Locally produced Mexican extracts have much lower total protein content and specific IgE binding capacity. These in vitro results must be complemented with other in vitro and in vivo skin prick tests to obtain a more complete picture of comparison of potency. Nevertheless results are quite consistent for the allergens tested here.

Respiratory atopy and domestic mite sensitization in Rio de Janeiro

Domestic mites occur in a significant percentage of homens in Rio de Janeiro, a tropical geographic region of Brazil. Local weather conditions (hot and humid) promote the significant mite proliferation. Objective. We are registering the allergic mite sensitization of a population with asthma and/or rhinitis living in this coastal area. Methods. A total of 600 patients with asthma and/or rhinitis aged>=2 years underwent 3,810 allergy skin tests (Multi-Test). Eight different extracts were applied: American house dust (Ahd), Brazilian house dust (Bhd), Dermatophagoides pteronyssinus (Dp), Dermatophagoides farinae (Df), Blomia tropicalis (Bt), Chortoglyhphus arcuatus (Ca), Aleuroglyphus ovatus (Ao) and Lepidoglyphus destructor (Ld). RAST to Dp, Bt, Ca, Ao and Ld were performed with sera of randomized 14 atopic subjects. Results A positive immediate skin test to at least one allergen was detected in 387 patients (64,5 percent). Domestic mite sensitization was documented in about 90 percent of the atopic individuals. Bt has unique antigens since 4.15 percent of the subjects had positive exclusive reactions. RAST analyses showed that both Dp and Bt are the most important local mite sensitizers with cross-reactivity to the other mites. Conclusion. This study confirms that domestic mites are the most prevalent local allergens associated with asthma and/or rhinitis. Sensitization to Bt was very common and it should be checked routinely for the diagnosis of respiratory atopy in Rio de Janeiro