Comparison between Newly Developed and Commercial Inhalant Skin Prick Test Reagents Using In Vivo and In Vitro Methods

Evaluation of The Safety and Efficacy of Newly Developed Domestic Allergenic Extracts for Skin Prick Testing

Background

Allergic disorders are common health problems worldwide with significant socio-economic impacts. The best diagnostic method using allergenic extract is the skin prick test. Regarding the effects of geo-climatic factors and allergenic extract source material quality, the aim of study was to determine the safety and efficacy of some in-house-developed allergenic extracts.

Methods

Forty-five different allergenic extracts, including common regional pollen, foods, and dog and cat hair, as well as positive and negative extracts, were prepared from domestic sources using optimum extraction methods. All extracts passed stability and sterility testing, and sterile final products containing 50% glycerin in 10 and 20 w/v concentrations were used. Skin prick testing was performed on volunteers and immediate or late side effects were recorded.

Results

In total, 56 students (mean age: 21.2±2.3y, M/F ratio: 1.07) participated in this study. For inhalant allergens, all extracts except dog hair extract caused positive responses. Salsola kali (Russian thistle) and Fraxinus velutina (ash tree) were the most common grass and tree pollen extracts, respectively. Of 18 different food extracts, five, including egg white, tomato, fig, melon, and green pepper caused skin reactivity in only one person. No participant reported any immediate or late side effects, including large local reaction or systemic response.

Conclusion

The result of the current study confirmed the safety of all our in-house-developed allergenic extracts. Regarding efficacy, almost all inhalant and five food allergens caused positive skin responses.

Precision Medicine in Mite Allergic Rhinitis

It is well-known that a correct diagnosis is necessary for effective treatment. In the case of allergic rhinitis due to mites, imprecise diagnosis with effective but improvable methods means that in many cases an optimal result is not reached in patients. The diagnosis of allergic rhinitis due to mite sensitization have to require more homogeneously reproducible diagnostic tests that try to encompass many more of the protein antigens contained in them. With the few proteins that the problem has usually focused on, there is no they would cover many of the clinically relevant allergens in a large proportion of patients. In this mini-review we try to highlight the importance of having good allergenic sources and briefly gather information on various allergenic proteins included in mites that could be clinically relevant. All this to try to get closer to a more accurate diagnosis. We are also talking about two diagnostic tools that are clearly out of use and that should be promoted in the consultations to obtain an even greater and better outcome in patients.

Comparison of Allergenic Properties among Commercially Available House Dust Mite Allergen Extracts in Korea

Precise allergy diagnosis and effective allergen specific immunotherapy are largely dependent on the quality of allergen extract. A new extract of Dermatophagoides farinae was commercially developed by Prolagen. The allergenic properties of the new extract were compared with those of other commercial products. The allergenic properties of the new extract were compared according to protein concentration, protein profiles, major allergen (Der f 1) contents, and allergenic potency to those for three commercially available extracts imported in Korea (Jubilant HollisterStier Allergy, Lofarma S.p.A., and Stallergenes Greer). Protein concentrations varied up to 2.62-fold (0.404 to 1.057 mg/mL), and Der f 1 contents varied up to 11.3-fold (3.597 to 40.688 μg/mL). Protein profiles of the extracts showed no major discrepancies, although there were some differences in SDS-PAGE band intensities, reflecting protein concentrations. Allergen potency ranged from 37038 to 60491 PAU/mL. The Prolagen product was highest in terms of protein concentration and allergen potency. The Lofarma product displayed Der f 1 content similar to that in Prolagen (19.4 μg/mg vs. 19.3 μg/mg). Endotoxin levels varied 8.9-fold (1020 to 8985 EU/mL). The newly developed house dust mite extract showed equal or better allergenic properties than available commercial extracts. This new product may be useful for better diagnostics and allergen-specific immunotherapeutics.

The role of allergen-specific IgE in predicting allergic symptoms on dog and cat exposure among Korean pet exhibition participants

BACKGROUND

The values of the skin prick test (SPT) and allergen-specific IgE (sIgE) measurement in predicting dog and cat allergies remain unclear. We aimed to evaluate the usefulness of SPT and sIgE measurement in predicting self-reported allergic symptoms during exposure to dogs and cats in Korean adults.

METHODS

A total of 552 participants in a pet exhibition in Korea completed questionnaires regarding exposure to dog or cat and the development of allergic symptoms during exposure. Study participants also underwent SPT using 3 different commercially available reagents, and had their blood drawn for measurement of serum total IgE and dog/cat-dander-IgE using ImmunoCAP®.

RESULTS

Measurement of sIgE for dog and cat dander allergens provided the highest positive and negative predictive values and sensitivity, but not specificity (58%, 87.2%, 67.9%, and 93.1% for allergic symptoms on dog exposure; 64.7%, 83.2%, 74.8%, and 88.9% for those on cat exposure, respectively), in predicting self-reported allergic symptoms on dog and cat exposure. The sIgE level consistently exhibited the highest area under the receiver operating characteristic curve (0.749 and 0.719 for allergic symptoms on dog and cat exposure, respectively). Careful interpretation of SPT and sIgE measurements maximized the positive and negative predictive values, sensitivity, and specificity for predicting allergic symptoms on dog exposure (71.4%, 87.3%, 75.3%, and 99.3%) and those on cat exposure (71.4%, 85.3%, 79.3%, and 98.9%).

CONCLUSIONS

The measurement of dog and cat dander sIgE levels may be useful for the exclusion of allergic symptoms related to pet exposure. Collective interpretation of SPT and sIgE tests facilitates identification of allergic symptoms on dog or cat exposure, giving a better rule-in test result.

Stability of extracts from pollens of allergenic importance in Korea

BACKGROUND/AIMS

Accurate diagnosis and the effects of allergen-specific immunotherapy for pollinosis are greatly dependent on the potency and stability of the extract. This study aimed to examine factors, such as temperature and storage buffer composition, that affect the stability of allergen extracts from pollens of allergenic importance in Korea.

METHODS

We prepared four pollen allergen extracts from ragweed, mugwort, Japanese hop, and sawtooth oak, which are the most important causes of seasonal rhinitis in Korea. Changes of protein and major allergen concentration were measured over 1 year by Bradford assay, two-site enzyme-linked immunosorbent assay, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis after reconstitution of the lyophilized allergen extract in various buffers and stored at room temperature (RT, 18°C to 26°C) or refrigerated (4°C).

RESULTS

More than 90% of the original protein concentration in all four extracts examined was detected over 1 year when 50% glycerol was added and refrigerated, whereas 57.9% to 94.5% remained in the extracts at RT. The addition of 50% glycerol to the storage buffer was found to prevent protein degradation at RT. Amb a 1, a major allergen of ragweed, was almost completely degraded in 9 weeks at RT when reconstituted in a buffer without 50% glycerol. However, 55.6% to 92.8% of Amb a 1 content was detected after 1 year of incubation at 4°C in all buffer conditions except 0.3% phenol.

CONCLUSION

Addition of 50% glycerol as well as refrigeration was found to be important in increasing the shelf-life of allergen extracts from pollens of allergenic importance.

Evaluation of major mite allergens from European standardized commercial extracts for in vivo diagnosis: addressing the need for precision medicine

Background

Skin prick testing is the first-line interventional method to diagnose IgE mediated allergic diseases. Methodological differences in manufacturing processes and extract standardization may lead to variations in the reagent quality and potency. The current study evaluates sixteen commercially available Dermatophagoides pteronyssinus and Blomia tropicalis extracts for allergy diagnosis from different European manufacturers regarding allergen composition and content and whether these differences could influence their biological activity.

Methods

Mite-allergic subjects (n = 21) were skin-tested with the extracts and studied for immunoglobulin E reactivity. Nine extracts from D. pteronyssinus and seven from B. tropicalis were analysed for total protein content by Bradford and ELISA double sandwich was used to quantify specific antibodies for D. pteronyssinus and B. tropicalis major allergens from nine different manufacturers.

Results

Mite extracts showed a 10–60 fold variation regarding the total protein content. The contents of the major allergens of D. pteronyssinus and B. tropicalis differed considerably (30–53 fold change) among the extracts. Blo t 5 was quantitatively present in < 50% of the of the B. tropicalis reagents and could not be clearly detected by immunoblotting in the majority of the B. tropicalis commercial extracts.

Conclusions

Certain natural D. pteronyssinus and B. tropicalis extracts lack important allergens showing a considerable variability in composition and content. A closer collaboration among clinicians, allergen manufacturing companies and regulatory agencies to improve the quality and consistency of D. pteronyssinus and B. tropicalis extracts is warranted to achieve a more precise diagnosis and treatment of house dust mite allergy.

Sensitivity and specificity of standardised allergen extracts in skin prick test for diagnoses of IgE-mediated respiratory allergies

Background

Skin prick tests (SPTs) are essential for the diagnosis of IgE-mediated allergy and are influenced by extract quality, biological potency and concentration of allergen.

Methods

In this open multicentre study 431 patients, aged 18-64 years were enrolled. Patients had a history of IgE-mediated allergy and a sensitisation (previous positive SPT of any manufacturer) against at least one of the investigated allergens: 6-grass pollen, house dust mite, birch and mugwort pollen. In our study, these allergens were tested in five concentrations each. To establish the optimal trade-off between sensitivity and specificity, the area under the receiver operating characteristic (ROC) curve was estimated by comparing the outcome of the SPT with three methods referred to as 'reference methods' (specific IgE, clinical case history and a previous SPT).

Results

For all allergens and reference methods, the area under the ROC curves were highly significant (p < 0.001). Specific IgE reference method resulted in the largest area under the curve (AUC) for all allergens (0.80-0.90) followed by previous SPT (0.70-0.87) and case history (0.65-0.74). Sensitivity of SPT increased with increasing concentration and specificity decreased. For all allergens, compared to specific IgE, the highest sensitivity (specificity at least 80%) was observed for the SPT solution of 50,000 Standardised Units (SU)/mL (grass pollen, birch pollen, house dust mite and mugwort).

Conclusion

In this study, with a large number of patients, it was demonstrated that clinical case history, previous SPT and specific IgE measurement could all be used as reference methods for the assessment of sensitivity/specificity of SPT solutions. The comparison of SPT with specific IgE resulted in the largest AUC. The highest sensitivity was observed for the SPT solution of 50,000 SU/mL.Trial registration EudraCT: 2006-005304-14.