SummaryA method for biological equilibration (BE) of allergen reference preparations using the skin‐prick test (SPT) method and histamine HCl 10 mg/ml as reference substance (reference method), was evaluated. The precision was low for weals less than 10 mm2. The slope (log weal area/log concentration) of allergen and histamine did not vary significantly between investigators and allergens. The median slopes were 0.39 (n= 384) and 0.34 (n= 397), for allergen and histamine, respectively (P < 0.01). The concentration of allergen eliciting a weal of the same size as that of histamine HCl 1 mg/ml (Chl) in the median sensitive patient, 1000 Biological Units/ml (BU/ml), did not vary significantly between clinics/geographical regions (grasses, mites and moulds). As BE is repeatable between regions. BUs estimated by this method are generally valid. A high correlation (r= 0.91, P < 0.001) was found between the median Chl as estimated with histamine 1 and 10 mg/ml as reference substance, respectively. Thus, this reference method for BE is valid. The precision of the SPT method with histamine HCl 1 mg/ml is not as good as with 10 mg/ml, which is therefore recommended as the reference concentration.

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Background: The physiochemical modification of allergens to reduce allergenicity, while retaining immunogenicity, provides a chance for the administration of higher doses of immunotherapy, with a decreased risk of systemic reactions. Objective: To evaluate the safety of doses of depigmented glutaraldehyde-polymerized vaccine of Dermatophagoides pteronyssinus increasing those used in normal clinical conditions in comparison with regular doses of a non-modified vaccine. Materials and Methods: The study was double-blind, parallel and included two patient groups. Twenty-three patients were treated weekly during 9 visits for the build-up phase, followed by 2-weekly maintenance doses (a total of 11 injections per patient). Eleven patients (mean age 22 years) received immunotherapy with the standardized modified vaccine. The maximum dose used was the result of depigmenting and polymerizing 100 times the maximum dose used with the native extract. The maximum concentration used was 990 µg/ml of freeze-dried material. Twelve patients (mean age 24 years) received a standardized, unmodified allergenic extract. The maximum concentration used was 70 µg of freeze-dried material/ml, with a potency of 10 HEP_L/ml. The tolerance was evaluated recording all the side reactions related to immunotherapy and graded following the recommendations of the European Academy of Allergology and Clinical Immunology. Results: In both groups, all immediate local reactions were clinically not relevant. Patients treated with the native extract experienced 42 local immediate and 24 delayed reactions (1 of them had a diameter >10 cm), whereas patients treated with the modified extract experienced 30 local immediate and 21 delayed reactions (2 of them had a diameter >10 cm). Four systemic reactions in 2 patients, 1 immediate of grade 1 and 3 delayed of grade 2 were reported in the group treated with native extract and 1 delayed of grade 2 in the group treated with the modified preparation. Conclusions: The modified extract of D. pteronyssinus, used at concentrations which are 10 times higher than those regularly administered in clinical practice, demonstrated to be safe to treat D. pteronyssinus-sensitive patients. The major ity of the local reactions (immediate and delayed) were clinically not relevant (diameter <5 cm). No systemic reactions of grade 3 or 4 were noted.

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A study was carried out on six subjects suffering from anaphylactic reactions including asthma, rhinoconjunctivitis, contact urticaria and hypotension following contact with rubber gloves. All of them showed skin sensitivity and serum specific IgE to various preparations of natural latex, and not to other chemicals used in glove manufacturing. Immunoblotting techniques demonstrated that at least four soluble polypeptides from natural latex had the ability to bind specific human IgE. The results suggested that natural latex proteins present in rubber gloves can cause severe specific hypersensitivity reactions.