**Core Concept**
The patient's severe atopic asthma is characterized by an overactive immune response to allergens, leading to chronic inflammation and airway hyperresponsiveness. This condition involves the release of various chemical mediators, including histamine, leukotrienes, and cytokines, which contribute to the pathophysiology of asthma.

**Why the Correct Answer is Right**
In atopic asthma, the immune system produces IgE antibodies in response to allergens, which leads to the activation of mast cells and the release of histamine. Histamine then binds to its receptors on smooth muscle cells, causing bronchoconstriction and increased mucus production. Furthermore, the release of cysteinyl leukotrienes (cysLTs) from mast cells and eosinophils also contributes to bronchoconstriction and inflammation. The correct answer reflects the increased levels of these chemical mediators in the blood of patients with atopic asthma.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not directly relate to the pathophysiology of atopic asthma. While cortisol has anti-inflammatory effects, it is not a direct consequence of the immune response in asthma.
**Option B:** This option is incorrect because it is not a direct consequence of the immune response in asthma. While eosinophils are involved in the pathophysiology of asthma, their numbers are not the most direct indicator of the disease process.
**Option C:** This option is incorrect because it is not a direct consequence of the immune response in asthma. While IgG antibodies are involved in the immune response, IgE is the primary antibody involved in atopic asthma.

**Clinical Pearl / High-Yield Fact**
In atopic asthma, the use of inhaled corticosteroids (ICS) is a cornerstone of treatment, as they reduce inflammation and prevent exacerbations. ICS work by inhibiting the release of histamine and other chemical mediators from mast cells, which helps to control symptoms and improve quality of life.

**Correct Answer: D. Elevated levels of histamine and cysteinyl leukotrienes.**