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 the preformed toxin involved in the mechanism of allergic rhinitis?

Histamine. ### Explanation The pathophysiology of Allergic Rhinitis is a **Type I Hypersensitivity reaction** mediated by IgE. When an allergen cross-links IgE antibodies on the surface of mast cells, it triggers **degranulation**, leading to the release of two types of inflammatory mediators: **1. Why Histamine is Correct:** Histamine is a **preformed mediator** stored in the granules of mast cells and basophils. Upon activation, it is released immediately (within minutes), causing the "Early Phase" response characterized by sneezing, itching, and rhinorrhea. Because it is synthesized and stored *before* the allergic trigger occurs, it is classified as a preformed toxin/mediator. **2. Why the Other Options are Incorrect:** * **Leukotrienes (B), TXA2 (C), and PGD2 (D):** These are **newly synthesized mediators** (lipid-derived). They are not stored in granules but are produced *de novo* from arachidonic acid via the cyclooxygenase (COX) or lipoxygenase (LOX) pathways only after the mast cell is activated. These mediators typically contribute to the "Late Phase" response, leading to nasal congestion and sustained inflammation. ### NEET-PG High-Yield Pearls: * **Early Phase (Minutes):** Primarily mediated by **Histamine**. Clinical features: Sneezing, itching, watery rhinorrhea. * **Late Phase (4–8 hours):** Mediated by **Leukotrienes (LTC4, LTD4, LTE4)**, Cytokines, and PGD2. Clinical feature: Nasal congestion (due to cellular infiltration, mainly eosinophils). * **Gold Standard Investigation:** Skin Prick Test (detects specific IgE). * **Drug of Choice:** Intranasal Corticosteroids (act on both early and late phases). * **Mast Cell Stabilizer:** Sodium Cromoglycate (prevents degranulation; used prophylactically).

Q: Paracusis willis is a feature of which condition?

Otosclerosis. **Explanation:** **Paracusis Willis** is a clinical phenomenon where a patient with hearing loss paradoxically hears better in a noisy environment than in a quiet one. **Why Otosclerosis is correct:** Otosclerosis is a condition characterized by the fixation of the stapes footplate, leading to **conductive hearing loss (CHL)**. In a noisy environment, normal-hearing individuals naturally raise their voice volume (the Lombard effect) to overcome background noise. A patient with Otosclerosis has a "conductive barrier" that filters out the low-frequency background noise, but because their inner ear and nerve function are intact, they can clearly perceive the loud, raised voices of others. This makes their hearing appear improved in noisy settings. **Why other options are incorrect:** * **Tympanosclerosis:** While this causes CHL due to hyalinization of the tympanic membrane, Paracusis Willis is classically described and most significantly associated with the stapes fixation found in Otosclerosis. * **Meniere’s Disease:** This is a sensory-neural hearing loss (SNHL) condition. Patients typically suffer from **loudness recruitment**, making noisy environments distressing rather than helpful. * **Presbyacusis:** This is age-related SNHL. These patients struggle significantly in noise due to poor speech discrimination and the loss of high-frequency clarity. **Clinical Pearls for NEET-PG:** * **Schwartz Sign:** A flamingo-pink flush seen on the promontory through the TM (indicates active otosclerosis/otospongiosis). * **Carhart’s Notch:** A characteristic dip in the bone conduction threshold at **2000 Hz**. * **Gelle’s Test:** Negative in Otosclerosis (indicates an immobile ossicular chain). * **Treatment of Choice:** Stapedotomy (using a Teflon piston).

Q: What is the full form of ARIA?

Allergic rhinitis and its impact on asthma. **Explanation:** **1. Why Option A is Correct:** ARIA stands for **Allergic Rhinitis and its Impact on Asthma**. It is a global initiative launched by the World Health Organization (WHO) in 1999 (published in 2001) to provide evidence-based guidelines for the management of allergic rhinitis. The core medical concept behind ARIA is the **"United Airway Disease"** hypothesis, which posits that the upper and lower airways are a single functional unit. Inflammation in the nasal mucosa (allergic rhinitis) often coexists with and exacerbates inflammation in the bronchial tree (asthma). **2. Why Other Options are Incorrect:** * **Option B:** While allergic rhinitis is a major risk factor for developing asthma, ARIA is the name of the *guideline/initiative*, not a description of the pathophysiology of "induced" asthma. * **Options C & D:** These are distractors. While ARIA guidelines discuss IgE-mediated antibody responses, the acronym itself does not stand for "Antibody Response." **3. High-Yield Clinical Pearls for NEET-PG:** * **Classification:** ARIA replaced the old "seasonal/perennial" classification with a more clinical approach based on duration and severity: * **Intermittent:** Symptoms 4 days/week AND > 4 consecutive weeks. * **Severity:** Categorized as **Mild** (normal sleep/daily activities) or **Moderate-Severe** (disturbed sleep/impairment of daily activities). * **Treatment Strategy:** Intranasal corticosteroids (INCS) are the first-line treatment for moderate-to-severe persistent rhinitis. * **The Link:** Approximately 80% of asthmatics have co-existing allergic rhinitis, and up to 40% of patients with allergic rhinitis have asthma. Treatment of the nose often improves asthma control.

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

Which of the following is the preformed toxin involved in the mechanism of allergic rhinitis?

Accepted Answer

Histamine

Answer

Leukotriene

Answer

TXA2

Answer

PGD2

Question 3

Paracusis willis is a feature of which condition?

Accepted Answer

Otosclerosis

Answer

Tympanosclerosis

Answer

Meniere's disease

Answer

Presbyacusis

Question 4

What is the full form of ARIA?

Accepted Answer

Allergic rhinitis and its impact on asthma

Answer

Allergic rhinitis induced asthma

Answer

Antibody response in allergic rhinitis

Answer

Antibody response in asthma

Question 5

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

Allergy and Immunotherapy — MCQs

Allergy and Immunotherapy — MCQs

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