Question

A 15-year-old girl with severe asthma triggered by seasonal allergies is receiving twice-monthly injections of a monoclonal antibody. Which mediator of asthma is antagonized by this drug? (A) immunoglobulin E (B) leukotriene \(\mathrm{C} 4\) (C) major basic protein (D) histamine (E) interleukin-2

Short answer

The mediator of asthma antagonized by the monoclonal antibody is Immunoglobulin E (IgE).

Step-by-step solution

Understanding the Context

The girl is receiving a monoclonal antibody treatment specifically for asthma exacerbated by allergies. Monoclonal antibodies used in asthma typically target specific immune molecules that contribute to the inflammatory process.

Identifying Possible Mediators

We need to recognize which mediators are typically targeted by monoclonal antibody therapies in the context of allergic asthma. Among the listed options, the main mediators often targeted are Immunoglobulin E (IgE), leukotrienes, and interleukins.

Matching the Right Mediator

The most common monoclonal antibody used for asthma related to allergies is omalizumab. This drug is specifically designed to antagonize Immunoglobulin E (IgE), a major contributor to allergic reactions and asthma exacerbation.

Conclusion

Given that omalizumab targets IgE and is used for treating asthma triggered by allergies, the mediator antagonized by the monoclonal antibody in this scenario is Immunoglobulin E.

Key concepts

Allergic Asthma

Allergic asthma is a type of asthma triggered by allergens such as pollen, dust mites, pet dander, and mold. These allergens stimulate an immune response, causing the airways to become inflamed and narrow, making it difficult to breathe. Symptoms often include wheezing, coughing, shortness of breath, and chest tightness.

People with allergic asthma have hypersensitive immune systems. When exposed to allergens, their bodies react by releasing chemicals that cause airway inflammation and mucus production.

• Avoiding known allergens can help manage symptoms.
• Using medications designed to reduce inflammation can also be effective.

In some cases, exposure to an allergen can trigger a severe asthma attack, requiring immediate medical attention. Thus, understanding the relationship between allergies and asthma is crucial for proper management and treatment.

Immunoglobulin E

Immunoglobulin E (IgE) is a type of antibody found in the immune system. It plays a key role in allergic reactions, particularly in allergic asthma. When the body is exposed to an allergen, IgE antibodies recognize and bind to it, which leads to the activation of immune cells.

This binding causes immune cells to release inflammatory mediators that lead to asthma symptoms. IgE is present in higher levels in people with allergies and asthma compared to those without these conditions.

• IgE antibodies are integral to the body's defense against foreign substances.
• However, their overactivity can lead to exaggerated immune responses, such as those seen in allergies.

Overall, controlling IgE levels can help in managing allergic asthma, thereby reducing the frequency and severity of asthma attacks.

Omalizumab

Omalizumab is a monoclonal antibody drug specifically designed to target Immunoglobulin E (IgE). By binding to IgE, omalizumab prevents it from attaching to immune cells, reducing the inflammatory response and alleviating asthma symptoms associated with allergy triggers.

This treatment is particularly beneficial for individuals whose asthma symptoms do not respond well to traditional medications. Omalizumab is administered as an injection, usually every two to four weeks, depending on the patient's condition.

• It is primarily prescribed for moderate to severe persistent allergic asthma.
• This treatment can significantly improve the quality of life by reducing asthma attacks and hospital visits.

However, omalizumab is not a rescue treatment; it is a long-term management option requiring consistent application under medical supervision.

Asthma Mediators

In the context of asthma, mediators are substances that play roles in the inflammatory response of the airways. They encompass a variety of molecules such as leukotrienes, histamines, cytokines, and IgE.

During an asthma attack, these mediators contribute to the constriction of airways, increase in mucus production, and swelling, causing the typical symptoms of asthma.

• Leukotrienes contribute to bronchoconstriction and increased mucus production.
• Histamines play a role in the immediate allergic response, leading to rapid symptoms onset.
• Cytokines promote long-term inflammation, perpetuating the asthmatic condition.

Targeting these different mediators via medications can help control asthma. For instance, leukotriene inhibitors and antihistamines may be used alongside monoclonal antibodies like omalizumab to offer comprehensive asthma management.