What causes an allergy to house dust mites? - briefly
Allergic reactions to dust‑mite exposure occur when the immune system generates IgE antibodies against proteins present in mite feces, bodies and secretions. Inhalation of these particles repeatedly provokes inflammation of the respiratory mucosa.
What causes an allergy to house dust mites? - in detail
Allergic reactions to house dust mites arise when the immune system mistakenly identifies specific mite proteins as harmful. The primary allergenic components are enzymatic proteins such as Der p 1, Der p 2, Der f 1, and Der f 2, which are present in mite feces, body fragments, and secretions. Upon inhalation, these proteins penetrate the respiratory epithelium and bind to IgE antibodies on mast cells and basophils, prompting the release of histamine, leukotrienes, and other mediators that cause typical allergy symptoms.
Sensitization requires repeated exposure in a conducive environment. High relative humidity (70–80 %) and warm temperatures (20–25 °C) support mite proliferation, increasing the concentration of allergenic particles in bedding, upholstery, and carpets. Poor ventilation, heavy carpeting, and insufficient cleaning elevate dust accumulation, thereby raising exposure levels.
Genetic predisposition influences the likelihood of developing a mite allergy. Individuals with a family history of atopic diseases—such as asthma, allergic rhinitis, or eczema—often exhibit heightened Th2 cell activity, elevated interleukin‑4 and interleukin‑13 production, and increased IgE synthesis. These immunological traits accelerate the sensitization process.
Additional factors modulate risk:
- Skin barrier defects: Impaired epidermal integrity, common in eczema, permits allergen entry and systemic sensitization.
- Co‑exposures: Pollutants, tobacco smoke, and microbial endotoxins can skew immune responses toward a Th2 phenotype.
- Age: Early childhood exposure, when immune regulation is still developing, correlates with higher sensitization rates.
Cross‑reactivity may occur with other arthropod allergens (e.g., cockroach, shrimp), because some mite proteins share structural similarities, leading to broader allergic profiles.
In summary, the development of an allergic response to house dust mites involves a combination of allergen protein exposure, environmental conditions that favor mite growth, genetic susceptibility that predisposes the immune system to a Th2‑dominant response, and ancillary factors that further amplify sensitization.