Allergy and Immunotherapy Practice Questions

Q: Which of the following are early mediators of allergic rhinitis?

Platelet-activating factor and bradykinin. ### Explanation Allergic rhinitis is a Type I hypersensitivity reaction occurring in two distinct phases: the **Early Phase** (within minutes) and the **Late Phase** (4–8 hours later). **Why Option D is Correct:** The early phase is triggered when an allergen cross-links IgE antibodies on the surface of **mast cells**, leading to immediate degranulation. This releases **pre-formed mediators** and rapidly synthesized lipid mediators. * **Histamine** is the primary mediator. * **Platelet-activating factor (PAF), Bradykinin, and Prostaglandin D2** are also released during this immediate window, causing vasodilation, increased vascular permeability (edema), and stimulation of sensory nerves (itching/sneezing). **Why Other Options are Incorrect:** * **A. Leukotrienes:** While Cysteinyl Leukotrienes (CysLTs) are produced during the early phase, they are most characteristic of the transition to and maintenance of the **Late Phase** response, contributing significantly to prolonged nasal congestion. * **B & C. Interleukin-4 and Interleukin-5:** These are **cytokines** produced by Th2 lymphocytes. They are involved in the **Late Phase** response. IL-4 promotes IgE isotype switching, while IL-5 is the primary factor for **eosinophil** recruitment and activation. **NEET-PG High-Yield Pearls:** 1. **Early Phase (Minutes):** Mediated by Mast cells. Key symptoms: Sneezing, itching, rhinorrhea. Key mediator: Histamine. 2. **Late Phase (Hours):** Mediated by Eosinophils, Basophils, and Th2 cells. Key symptom: Nasal congestion. 3. **Gold Standard Diagnosis:** Skin Prick Test (detects specific IgE). 4. **Pharmacology Link:** Antihistamines work best on early-phase symptoms (itch/sneeze), while Intranasal Steroids are the most effective treatment for late-phase symptoms (congestion) because they inhibit cytokine release.

Q: Which of the following is NOT a second-generation antihistamine used in allergic rhinitis?

Chlorpheneramine maleate. **Explanation:** The classification of antihistamines (H1-receptor antagonists) is a high-yield topic in ENT and Pharmacology. They are primarily divided into two generations based on their ability to cross the blood-brain barrier and their sedative profiles. **Why Chlorpheniramine maleate is the correct answer:** Chlorpheniramine maleate is a **First-generation antihistamine**. These drugs are highly lipophilic and readily cross the blood-brain barrier, leading to significant sedation and psychomotor impairment. They also possess significant anticholinergic properties (causing dry mouth, urinary retention, and blurred vision). **Analysis of Incorrect Options (Second-generation Antihistamines):** Second-generation agents are more peripherally selective, less lipophilic, and generally non-sedating. * **Azelastine:** A second-generation antihistamine often used as a topical nasal spray. It has the added benefit of mast-cell stabilizing and anti-inflammatory properties. * **Fexofenadine:** A highly selective second-generation agent (the active metabolite of terfenadine) known for being the least sedating of the group. * **Desloratadine:** A potent, long-acting second-generation antihistamine (the active metabolite of loratadine). **NEET-PG Clinical Pearls:** * **Drug of Choice:** Second-generation antihistamines are the first-line oral treatment for mild-to-moderate Allergic Rhinitis due to their superior safety profile. * **Topical Advantage:** Azelastine nasal spray has a faster onset of action (approx. 15 mins) compared to oral antihistamines. * **Side Effects:** First-generation agents (like Chlorpheniramine and Diphenhydramine) are contraindicated in patients with narrow-angle glaucoma and prostatic hypertrophy due to their anticholinergic effects. * **Metabolites:** Remember that **Cetirizine** is the metabolite of Hydroxyzine, and **Fexofenadine** is the metabolite of Terfenadine.

Q: All are correct about the technique of administration of intranasal steroids for severe allergic rhinitis EXCEPT:

Point to inner canthus of eye toward the septum of nose. ***Point to inner canthus of eye toward the septum of nose*** - Directing the spray towards the **inner canthus of the eye** (which points towards the nasal septum) should be **avoided**. - This incorrect technique leads to the steroid being sprayed directly onto the **nasal septum**, increasing the risk of septal irritation, crusting, and epistaxis. - **Proper technique requires directing spray AWAY from the septum** towards the lateral nasal wall. *Nostril of device to be directed into inferior turbinate* - Correct administration of **intranasal steroids** involves aiming the spray towards the **lateral wall of the nasal cavity**, specifically targeting the inferior turbinate. - This technique maximizes drug deposition on the most reactive allergic mucosa while minimizing septal contact. *Use right hand for left nostril and vice versa* - The **cross-hand technique** is recommended to help direct the spray more effectively towards the lateral nasal wall and away from the septum. - This method naturally angles the spray bottle towards the turbinates rather than the septum. *Use optimally for 3 months to avoid local and systemic complications* - **Intranasal corticosteroids** are generally safe for **long-term use** (many months to years) for managing chronic allergic rhinitis. - Limiting use to only 3 months is unnecessary, though this statement about optimal duration is less critical than the technique errors.

Question 1

Which of the following are early mediators of allergic rhinitis?

Accepted Answer

Platelet-activating factor and bradykinin

Answer

Leukotrienes

Answer

Interleukin-4

Answer

Interleukin-5

Question 2

A 29-year-old non-smoker man presents with sneezing, post-nasal drip, eye watering, and itching of his posterior pharynx. These symptoms tend to be worse in the spring and summer and have been bothering him for about 1 month. His past medical history is remarkable only for mild asthma induced by being outdoors. He takes no regular medications but does take diphenhydramine on occasion. What is the most appropriate diagnostic test at this time?

Accepted Answer

None, the diagnosis is based solely on the history and physical examination

Answer

Blood radioallergosorbent test

Answer

Intradermal testing

Answer

Serum protein electrophoresis

Question 3

Which of the following is NOT a second-generation antihistamine used in allergic rhinitis?

Accepted Answer

Chlorpheneramine maleate

Answer

Azelastine

Answer

Fexofenadine

Answer

Desloratidine

Question 4

All are correct about the technique of administration of intranasal steroids for severe allergic rhinitis EXCEPT:

Accepted Answer

Point to inner canthus of eye toward the septum of nose

Answer

Nostril of device to be directed into inferior turbinate

Answer

Use right hand for left nostril and vice versa

Answer

Use optimally for 3 months to avoid local and systemic complications

Allergy and Immunotherapy — MCQs

Allergy and Immunotherapy — MCQs

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