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Published on: May 30, 2020
Isolation and characterization of a novel 98-kd Dermatophagoides farinae mite allergen
1Department of Medical Research, Veterans General Hospital-Taipei, Taiwan, Republic of China.
Background:
Exposure to allergens from house dust mites is a significant cause of immediate hypersensitivity. Thus far, the active mite allergens defined are low molecular weight (MW) proteins or glycoproteins. However, other important mite allergens remain to be investigated. In this study a high MW mite antigen with a high IgE-binding activity was characterized.
Methods:
An anti-Dermatophagoides farinae (Df) monoclonal antibody, mAb642, which recognized a 98-kd allergenic mite protein, was used for affinity chromatography. The purified Df642 was characterized biochemically and immunologically.
Results:
Competitive ELISA demonstrated that mAb642 was inhibited by the interaction between serum IgE from allergic patients and Df642 antigen in a dose-dependent fashion. The IgE reactivity to both 98-kd and 92-kd components was removed or diminished by preincubation of asthmatic sera with Df642-coated CNBr-activated cellulose-4B gel. Two-dimensional immunoblot analysis revealed that there are at least 4 isoforms of Df642 that represent a minor component in the crude mite extract. The allergenicity of Df642 was assayed by IgE immunoassay with a large panel of 67 sera from asthmatic patients with positive skin reactions, and Df 642 showed positive IgE reactivity with more than 80% of the sera tested. Thus it should be classified as an important allergen. In addition, amino acid sequence analysis revealed that Df642 shares more than 50% homology with paramyosin from invertebrates.
Conclusion:
We have identified and characterized a 98-kd house dust mite allergen that showed greater than 80% IgE reactivity with sera from patients allergic to mites. This is the first high MW allergen characterized to date, and it shares high sequence homology with paramyosins in invertebrates.
Insights
A new high molecular weight (MW) house dust mite allergen, Df642, has been identified. This significant allergen shows over 80% IgE reactivity in allergic patients and shares homology with invertebrate paramyosins.
Area of Science:
- Immunology
- Allergology
- Molecular Biology
Background:
- House dust mite allergens are a primary cause of immediate hypersensitivity.
- Known allergens are typically low MW proteins or glycoproteins.
- The characterization of high MW allergens remains underexplored.
Purpose of the Study:
- To identify and characterize a novel high MW allergen from house dust mites.
- To assess the IgE-binding activity and allergenic potential of this new antigen.
Main Methods:
- Affinity chromatography using a specific monoclonal antibody (mAb642) to purify the 98-kd protein (Df642).
- Biochemical and immunological characterization, including competitive ELISA and 2D immunoblot analysis.
- IgE immunoassay using sera from 67 asthmatic patients.
Main Results:
- Df642 demonstrated significant IgE reactivity with over 80% of sera from mite-allergic asthmatic patients.
- Two-dimensional immunoblot revealed at least 4 isoforms of Df642.
- Amino acid sequence analysis indicated over 50% homology with invertebrate paramyosins.
Conclusions:
- A 98-kd house dust mite allergen (Df642) with high IgE reactivity has been identified and characterized.
- This represents the first high MW allergen identified, highlighting its importance in mite allergy.
- The homology to paramyosins suggests potential cross-reactivity and novel insights into allergen structure.
