CCD Inhibition Test Can Improve the Accuracy of the Detection of Pollen and Seed Food Allergen-Specific IgE in Southern China

Food-Pollen Cross-Reactivity and its Molecular Diagnosis in China

PURPOSE OF REVIEW

Plant-derived foods are one of the most common causative sources of food allergy in China, with a significant relationship to pollinosis. This review aims to provide a comprehensive overview of this food-pollen allergy syndrome and its molecular allergen diagnosis to better understand the cross-reactive basis.

RECENT FINDINGS

Food-pollen cross-reactivity has been mainly reported in Northern China, Artemisia pollen is the major related inhalant source, followed by tree pollen (Betula), while grass pollen plays a minor role. Pollen allergy is relatively low in Southern China, with allergies to grass pollen being more important than weed and tree pollens. Rosaceae fruits and legume seeds stand out as major related allergenic foods. Non-specific lipid transfer protein (nsLTP) has been found to be the most clinically relevant cross-reacting allergenic component, able to induce severe reactions. PR-10, profilin, defensin, chitinase, and gibberellin-regulated proteins are other important cross-reactive allergen molecules. Artemisia pollen can induce allergenic cross-reactions with a wide range of plant-derived foods in China, and spring tree pollens (Betula) are also important. nsLTP found in both pollen and plant-derived food is considered the most significant allergen in food pollen cross-reactivity. Component-resolved diagnosis with potential allergenic proteins is recommended to improve diagnostic accuracy and predict the potential risk of causing allergic symptoms.

Selected Technical Aspects of Molecular Allergy Diagnostics

Diagnosis of allergic diseases is a complex, multi-stage process. It often requires the use of various diagnostic tools. The in vitro diagnostics (IVD), which includes various laboratory tests, is one of the stages of this process. Standard laboratory tests include the measurement of the serum concentration of specific immunoglobulin E (sIgE) for selected allergens, full allergen extracts and/or single allergen components (molecules). The measurement of IgE sIgE to the allergen components is called molecular allergy diagnosis. During the standard laboratory diagnostic process, various models of immunochemical tests are used, which enable the measurement of sIgE for single allergens (one-parameter tests, singleplex) or IgE specific for many different allergens (multi-parameter tests, multiplex) in one test. Currently, there are many different test kits available, validated for IVD, which differ in the method type and allergen profile. The aim of the manuscript is to present various technical aspects related to modern allergy diagnostics, especially in the area of molecular allergy diagnostics.

Molecular diagnostics and inhibition of cross‐reactive carbohydrate determinants in Hymenoptera venom allergy

Background

The composition of venom extracts, cross‐reactive carbohydrate determinants (CCD) and the component‐resolved diagnostics (CRD) are important fields of investigation. IgE‐reactivity to CCD complicates the interpretation of IgE to Hymenoptera venoms, especially in patients with multiple‐positivity. We analyzed the clinical importance of CRD and CCD‐inhibition for selection of allergens for venom immunotherapy (VIT).

Methods

In 71 patients, we measured specific IgE (sIgE) to honeybee venom (HBV), wasp venom (WV), hornet venom (HV), CCD, and recombinant allergens: phospholipase A2 (rApi m 1), hyaluronidase (rApi m 2), icarapin (rApi m 10), antigen 5 (rVes v 5), and phospholipase A1 (Immunoblot). In 29/71 HBV/WV/HV/CCD‐positive patients CCD‐inhibition was performed. According to CRD and CCD‐inhibition, we identified true sensitization and defined groups of multiple‐positive patients who needed CCD‐inhibition before starting VIT.

Results

sIgE‐rApi m 1, sIgE‐rApi m 2, and sIgE‐rApi m 10 were detected in 65.7%, 68.4%, and 58%, respectively. In HBV allergic patients, CRD sensitivity was 86.8%. In WV allergic patients, sensitivity of sIgE‐rVes v 5 was 94%. True multiple‐sensitization was found in 44.8% of HBV/WV/HV/CCD‐positive patients after CCD‐inhibition. Patients with multiple venom‐ and CCD‐positivity had more frequent severe allergic reactions (p < 0.001). CCD‐inhibition was helpful in HBV/WV/HV/CCD‐positive patients who were negative to all tested recombinant honeybee allergens. Persistence of HBV‐positivity after CCD‐inhibition requires CRD to other honeybee recombinant allergens.

Conclusion

CRD, using a profile of five most important recombinant allergens and CCD, has a high sensitivity for the diagnosis of venom allergy, especially in patients positive to several venom extracts. CRD and CCD‐inhibition are helpful to reveal the clinically relevant, true sensitization and improve the selection of venoms for long‐lasting VIT.

Cross-Reacting Carbohydrate Determinants Inhibitor Can Improve the Diagnostic Accuracy in Pollen and Food Allergy

Background

Cross-reacting carbohydrate determinants (CCD) exist in some pollen and food allergens, but they do not contribute to allergic symptoms. However, CCD can induce specific IgE (sIgE) production and may lead to incorrect allergen diagnosis and treatment. CCD inhibitor is a specific antibody adsorbent which can preclude CCD from binding to sIgE. Currently, the data of CCD inhibition in allergen sIgE test are limited.

Methods

The allergic patients with positive skin prick reactions to two or more pollen and/or food allergen extracts were included in our study. Their sera were obtained and sIgE was tested with an allergen panel that included 29 single and mixed allergens (MEDIWISS Analytic GmbH, China) before and after CCD inhibition. The changes of sIgE against these allergens and the correlations of sIgEs to clinical symptoms were analyzed.

Results

A total of 44 patients were included and 36 (81.82%) of those were multi-sensitized to house dust mites and pollen allergens based on skin prick tests. The sIgE levels and positive rates against most pollen and food allergens were significantly lower after CCD inhibition. The sIgE levels of pollen were positively correlated to those of food allergens before CCD inhibition. However, these correlations were weakened or no longer existed after CCD inhibition. The sIgE against pollen and food allergens showed significantly higher consistency with clinical symptoms after CCD inhibition.

Conclusion

Cross-sensitization caused by CCD is widespread in pollen and food. CCD inhibition test can improve the diagnostic accuracy of pollen and food allergy.

Three patterns of sensitization to mugwort, timothy, birch and their major allergen components revealed by Latent class analysis

BACKGROUND

Mugwort, timothy, and birch are commonly spread pollen allergens across China. Although several studies have described the rates of sensitization to mugwort, timothy, and birch in China, most of them just on specific whole-allergen extracts but little was known about the co-sensitization characteristics of its allergen components. This study aimed to explore the patterns of sensitization to mugwort, timothy, birch, and their major allergen components.

METHOD

Serum specific IgE (sIgE) levels of allergen components of mugwort, timothy, birch, and cross-reactive carbohydrate determinants (CCD) were detected in 160 patients whose serum showed positive results to at least one of mugwort, timothy, and birch allergens via EUROBlotMaster system. Skin prick testing was utilized to assess the allergic reaction of grass, weed, and tree allergens. Latent class analysis was used to identify underlying patterns of sensitization to a series of allergen components and their corresponding extracts.

RESULTS

88.8% of patients with allergic rhinitis and/or asthma were positive for mugwort-sIgE, 30% for timothy-sIgE, and 32.5% for birch-sIgE. By using the LCA model, three sensitization patterns as "Mugwort, Art v 4, Bet v 2 and Phl p 12 co-sensitized", "Timothy, mugwort, and CCD co-sensitized", "Mugwort and Art v 1 co-sensitized" were revealed based on optimal statistical fit in this study. Compared with other clusters, participants in "Mugwort, Art v 4, Bet v 2 and Phl p 12 co-sensitized" pattern were associated with higher sensitization rates of common grass and tree pollens allergen. The spearman's coefficient between CCD and timothy was larger than the corresponding values of CCD with mugwort or birch.

CONCLUSION

CCD and profilin, as minor allergens in pollens, were associated with other pollen sIgE false positives presumably due to cross-reactivity. Patients sensitized with profilin had a significantly higher risk of sensitization to other pollens.

Major Grass Pollen Allergen Components and Cross-Reactive Carbohydrate Determinants in Mugwort-Sensitized Child Patients With Allergic Respiratory Disease in Western China

Mugwort is a common pollen allergen in western China, and this study aimed to investigate the patterns of molecular sensitization to major grass pollen allergens (mugwort, ragweed, bermuda grass, and timothy grass) and cross-reactive carbohydrate determinants (CCD) in children who were sensitized to mugwort in western China. Serum-specific IgE (sIgE) of major allergen components and CCD were detected among 121 mugwort SPT-positive children via the EUROBlotMaster system if the mugwort-sIgE was positive (MSP). A CCD inhibition test was further performed on the serum of patients with positive CCD-sIgE. Latent class analysis was used to identify the patterns of potential sensitization to major grass pollen allergens. Of a total of 100 patients with mugwort-sIgE positive (MSP), 52.0, 41.0, and 31.0% of them were positive to Art v 1, Art v 3, and Art v 4, respectively. An optimal model with three latent classes was determined using grass pollen allergens, components, and CCD. The sensitization patterns can be summarized as (1) MSP and cosensitized to ragweed, bermuda grass, and timothy grass (23.74%); (2) MSP and cosensitized to Art v 1 (54.08%); (3) MSP and cosensitized to Art v 4, Cyn d 12, Phl p 12 (22.18%). Additionally, CCD sIgE levels had a significant positive correlation with ragweed, bermuda grass, and timothy grass (P < 0.05), and CCD-Inhibitor can highly inhibit the above allergens sIgE. Our findings suggest that Art v 4 was the typical cross-reaction component of mugwort, which is cosensitized to Phl p 12 and Cyn d 12. A wide cross-reaction among ragweed, bermuda grass, and timothy grass caused by CCD was observed.

Analysis of Peanut Allergen Components Sensitization and Cross Reaction with Pollen Allergen in Chinese Southerners with Allergic Rhinitis and/or Asthma

Objective

Peanut is one of the most frequently reported allergens causing severe allergies in western countries. In China, however, there have been few reports of severe allergies caused by peanuts. We investigated the peanut allergen components sensitization and cross-reaction with pollen allergen in Chinese Southerners with allergic rhinitis and/or asthma.

Methods

Total IgE (tIgE) and specific IgE (sIgE) antibodies against Ara h 1, Ara h 8, Juglans pollen, Platanus pollen, birch pollen, Bet v 1, Bet v 4, and cross-reactive carbohydrate determinant (CCD) of 58 allergic patients, of whom 33 were peanut-sIgE positive and 25 were negative, were detected by the ImmunoCAP system. The relationships between peanut allergen and pollen allergens were analyzed.

Results

A 9.1% (3/33) of the patients with peanut sensitization were sensitized to Ara h 8, while 21.2% (7/33) were sensitized to Ara h 1. The peanut-sensitized group had significantly higher positive rates for sIgE antibodies against CCD (69.7% vs 4.0%), Juglans pollen (87.9% vs 12.0%), Platanus pollen (90.9% vs 16.0%), and birch pollen (60.6% vs 4.0%) than the peanut tolerance group (all P < 0.05). Spearman correlation showed that peanut-sIgE were significantly correlated with sIgE to CCD (r_s=0.859), Juglans pollen (r_s=0.772), Platanus pollen (r_s=0.838) and birch pollen (r_s=0.816).

Conclusion

The majority of patients sensitized to peanut allergen in Southern China tested positive for multiple pollen allergens. Peanut sensitization was highly correlated with Platanus, Juglans, and birch pollen sensitization, which suggested there may be cross-reactions between peanut and pollen allergens. Clinicians should pay attention to distinguish diagnosis in clinical peanut allergy diagnosis and treatment.