The sequence of mast cell and eosinophil activation, influenced by allergen exposure, is pivotal in determining the varied symptoms observed in Type I allergies, ranging from respiratory issues to vascular symptoms. Here option C is correct.
The variety of symptoms observed in different Type I allergies is primarily dependent on factors related to the immune response triggered by allergen exposure. Among the options provided, the most relevant factor is (c) whether mast cells or eosinophils are activated first in response to the allergen.
In Type I allergies, such as allergic rhinitis or asthma, allergens stimulate the production of specific IgE antibodies. These IgE antibodies bind to mast cells and eosinophils. When the allergen is encountered again, it cross-links with IgE on the surface of these cells, leading to their activation.
The type of cells activated first influences the release of different mediators and, subsequently, the symptoms manifested. Mast cells release histamine and other inflammatory molecules, contributing to respiratory symptoms like wheezing and nasal congestion.
Eosinophils release substances that can cause vascular symptoms and contribute to tissue damage. Therefore, the localization and sequence of mast cell and eosinophil activation play a crucial role in determining the diverse symptoms seen in Type I allergies. Here option C is correct.