Which of the following is a common feature of type 2 asthma?

The correct choice focuses on the elevated levels of eosinophils, which is a hallmark characteristic of type 2 asthma. Type 2 asthma, often referred to as allergic asthma, is associated with an eosinophilic inflammatory response in the airways. Eosinophils are a type of white blood cell that play a significant role in the immune response and are prominently involved in allergic reactions and inflammation. In patients with type 2 asthma, these cells are often elevated, indicating an underlying allergic process that contributes to airway hyperreactivity and inflammation.

This feature helps differentiate type 2 asthma from other forms of asthma, as eosinophilia is indicative of an allergic or atopic response. Understanding this characteristic is crucial for treating type 2 asthma, as therapies may target eosinophilic inflammation via corticosteroids or biologics designed to reduce eosinophil levels, improving asthma control and reducing exacerbations.

In context, the other options do not reflect core attributes of type 2 asthma. For instance, type 2 asthma can occur at various ages, and while it is often identified in childhood, it can also emerge later in life (thus not indicating late onset specifically). Similarly, allergenic factors are highly relevant in type