I85PREP
⌘ K
ABAI study materials
ABAI study resources

ABAI practice questions

One question at a time. Build your ABAI understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Allergy

Which immunoglobulin is responsible for the immediate wheal-and-flare reaction seen in skin prick testing?

  1. Immunoglobulin A
  2. Immunoglobulin G
  3. Immunoglobulin E Correct answer.
  4. Immunoglobulin M

Explanation

Skin prick testing introduces allergen that cross-links allergen-specific IgE bound to mast cells, triggering degranulation and a wheal-and-flare response within minutes. Other isotypes do not mediate this immediate mast cell response.

Question 2Allergy

Approximately how long after allergen exposure does a type I immediate hypersensitivity reaction typically begin in a sensitized individual?

  1. Within minutes Correct answer.
  2. Within 4 to 6 hours
  3. After 72 hours
  4. After 24 to 48 hours

Explanation

IgE-mediated immediate hypersensitivity develops within minutes of allergen exposure because preformed mediators are released from mast cells upon cross-linking of surface IgE. Later phases may follow but the initial reaction is rapid.

Question 3Allergy

A patient reports sneezing, clear rhinorrhea, and nasal itching that worsen each spring. Which mediator is most directly responsible for the itching and sneezing of allergic rhinitis?

  1. Leukotriene B4
  2. Bradykinin
  3. Prostaglandin I2
  4. Histamine Correct answer.

Explanation

Histamine released from mast cells binds H1 receptors on sensory nerves and causes itching and sneezing, and also promotes vasodilation and secretion. This is why H1 antihistamines relieve these symptoms.

Question 4Allergy

Which finding on spirometry is characteristic of asthma?

  1. A restrictive pattern with normal FEV1/FVC ratio
  2. A fixed reduction in FEV1 that does not change with bronchodilator
  3. A reduced diffusing capacity
  4. A reduced FEV1/FVC ratio that improves after bronchodilator Correct answer.

Explanation

Asthma produces an obstructive pattern with a reduced FEV1/FVC ratio, and reversibility is demonstrated by improvement in FEV1 after a short-acting bronchodilator. This reversibility distinguishes asthma from fixed obstruction.

Question 5Allergy

Which of the following is the first-line controller medication for persistent asthma in most adults?

  1. Long-acting beta-2 agonist alone
  2. Oral theophylline
  3. Montelukast alone
  4. Inhaled corticosteroid Correct answer.

Explanation

Inhaled corticosteroids are the most effective long-term controller for persistent asthma because they reduce airway inflammation. Other agents are generally add-ons or alternatives rather than first-line monotherapy.

Question 6Allergy

A child develops hives, lip swelling, and wheezing within minutes of eating peanuts. Which medication is the first-line treatment for this reaction?

  1. Inhaled albuterol
  2. Oral diphenhydramine
  3. Intramuscular epinephrine Correct answer.
  4. Oral prednisone

Explanation

Intramuscular epinephrine is the first-line treatment for anaphylaxis because it rapidly reverses vasodilation, mucosal edema, and bronchospasm. Antihistamines and corticosteroids are adjuncts and do not treat airway compromise.

Question 7Allergy

Which test is the most appropriate initial evaluation for suspected IgE-mediated food allergy to a specific food?

  1. Eosinophil count
  2. Skin prick test with the suspected food Correct answer.
  3. Total serum IgE level
  4. Serum tryptase level

Explanation

A skin prick test with the suspected allergen detects specific IgE sensitization and is a standard initial test for IgE-mediated food allergy. Total IgE and eosinophil counts are nonspecific.

Question 8Allergy

Which of the following is a recognized risk factor for fatal anaphylaxis from a food allergy?

  1. Concurrent asthma Correct answer.
  2. Regular use of inhaled saline
  3. Mild seasonal rhinitis
  4. Well-controlled eczema

Explanation

Comorbid asthma, particularly poorly controlled asthma, is a well-established risk factor for severe and fatal food-induced anaphylaxis. Other atopic conditions alone do not carry the same risk.

Question 9Allergy

A patient with allergic rhinitis has symptoms poorly controlled on an intranasal corticosteroid. Which addition is most appropriate for persistent moderate-to-severe symptoms?

  1. An oral decongestant
  2. An oral corticosteroid course
  3. An intranasal antihistamine Correct answer.
  4. An inhaled beta-2 agonist

Explanation

Combining an intranasal antihistamine with an intranasal corticosteroid improves symptom control in patients not responding adequately to corticosteroid alone. Decongestants and systemic steroids are not preferred long-term additions.

Question 10Allergy

A patient reports urticaria and wheezing during exercise only after eating celery. Which mechanism best explains this presentation?

  1. Food-dependent exercise-induced anaphylaxis Correct answer.
  2. Cold urticaria
  3. Cholinergic urticaria
  4. Chronic spontaneous urticaria

Explanation

Food-dependent exercise-induced anaphylaxis occurs when a sensitizing food is eaten shortly before exercise, and neither the food nor exercise alone triggers the reaction. This pattern distinguishes it from other physical urticarias.

Question 11Allergy

Which statement about the mechanism of allergen immunotherapy is most accurate?

  1. It shifts the immune response toward allergen-specific IgG and regulatory T-cell activity Correct answer.
  2. It works by blocking histamine H1 receptors
  3. It raises total serum IgE to protective levels
  4. It permanently depletes mast cells from mucosal tissue

Explanation

Allergen immunotherapy induces allergen-specific IgG, particularly IgG4, and promotes regulatory T-cell responses that suppress IgE-mediated reactivity. This immunologic modification underlies its long-term benefit.

Question 12Allergy

A patient has a large local reaction to an insect sting with swelling extending over a joint but no systemic symptoms. What is the recommended management?

  1. Immediate intramuscular epinephrine
  2. Immediate venom immunotherapy
  3. Reassurance and symptomatic treatment, since large local reactions are not anaphylaxis Correct answer.
  4. Lifelong oral corticosteroid therapy

Explanation

Large local reactions are not life-threatening and are managed with reassurance and symptomatic measures such as antihistamines and local care. They do not require epinephrine or immunotherapy.

Question 13Allergy

Which of the following best distinguishes allergic from nonallergic rhinitis?

  1. Symptom severity
  2. Response to intranasal corticosteroids
  3. Presence of allergen-specific IgE sensitization Correct answer.
  4. Presence of nasal eosinophilia

Explanation

Allergic rhinitis is defined by IgE-mediated sensitization to aeroallergens, demonstrated by skin or serologic testing. Nonallergic rhinitis lacks this specific sensitization even though symptoms may be similar.

Question 14Allergy

A patient with asthma uses a short-acting beta-2 agonist more than two days per week but has no night symptoms and normal lung function. How is asthma control best classified?

  1. Well controlled
  2. Very poorly controlled
  3. Not well controlled Correct answer.
  4. Uncontrolled severe asthma

Explanation

Reliever use more than two days per week exceeds the threshold for well-controlled asthma and places the patient in the not well controlled category. Well-controlled asthma requires infrequent reliever use among other criteria.

Question 15Allergy

Which test is most useful for confirming the diagnosis of chronic spontaneous urticaria when the history is typical?

  1. Skin prick testing to aeroallergens
  2. Serum total IgE
  3. Routine food-specific IgE panel
  4. No specific test is required; the diagnosis is clinical Correct answer.

Explanation

Chronic spontaneous urticaria is diagnosed clinically when recurrent wheals occur for more than six weeks without an identifiable external trigger. Extensive allergy testing is not routinely helpful and can produce misleading results.

Question 16Allergy

A patient with a history of anaphylaxis to penicillin needs a cephalosporin. Which approach is most appropriate?

  1. Assess cross-reactivity risk and consider allergy evaluation or a graded challenge based on the specific cephalosporin Correct answer.
  2. Give the cephalosporin immediately without any precaution
  3. Give oral antihistamine before the cephalosporin and proceed routinely
  4. Avoid all beta-lactams permanently without evaluation

Explanation

Cross-reactivity between penicillins and cephalosporins depends on side-chain structure, so risk should be assessed and management individualized, sometimes with allergy testing or a graded challenge. Reflexive permanent avoidance of all beta-lactams is not appropriate.

Question 17Allergy

Which of the following is the most appropriate action for a patient with a documented IgE-mediated allergy to a food who accidentally ingests a small amount and develops only mild oral itching?

  1. Treat with an oral antihistamine and monitor for progression Correct answer.
  2. Give intramuscular epinephrine immediately
  3. Induce vomiting
  4. Give an oral corticosteroid alone and discharge

Explanation

Isolated mild oral itching without systemic features may be managed with an antihistamine while monitoring for progression, with epinephrine reserved for systemic involvement. The patient should have an emergency plan and epinephrine available.

Question 18Allergy

Which of the following best describes the role of serum-specific IgE testing compared with skin prick testing in allergy diagnosis?

  1. Serum testing directly measures mast cell degranulation
  2. Both detect sensitization, but neither alone establishes clinical allergy without correlating with history Correct answer.
  3. Skin prick testing measures total IgE
  4. Serum-specific IgE is always more sensitive than skin testing

Explanation

Both skin prick and serum-specific IgE tests detect allergen sensitization, but sensitization does not equal clinical allergy. Results must be interpreted alongside a compatible history.

Question 19Allergy

A patient with asthma and aspirin sensitivity also has nasal polyps. Which condition does this triad represent?

  1. Vocal cord dysfunction
  2. Allergic bronchopulmonary aspergillosis
  3. Eosinophilic granulomatosis with polyangiitis
  4. Aspirin-exacerbated respiratory disease Correct answer.

Explanation

Aspirin-exacerbated respiratory disease is characterized by asthma, aspirin or NSAID sensitivity, and nasal polyposis. It is driven by abnormal arachidonic acid metabolism rather than IgE.

Question 20Allergy

Which of the following is the most appropriate recommendation for a patient with a history of systemic anaphylaxis to a food?

  1. Use daily oral corticosteroids
  2. Carry an epinephrine autoinjector and have an emergency action plan Correct answer.
  3. Avoid all outdoor activities
  4. Carry only an oral antihistamine

Explanation

Patients with a history of food-induced anaphylaxis should carry epinephrine and follow a written emergency action plan because epinephrine is the only first-line treatment for anaphylaxis. Antihistamines alone are inadequate.

Question 21Allergy

A patient with chronic rhinosinusitis and asthma is found to have peripheral eosinophilia and elevated IgE. Which additional finding would most support allergic bronchopulmonary aspergillosis?

  1. Low total IgE
  2. A normal chest radiograph
  3. Central bronchiectasis with Aspergillus-specific IgE Correct answer.
  4. Negative Aspergillus precipitins

Explanation

Allergic bronchopulmonary aspergillosis is characterized by Aspergillus sensitization, elevated IgE, eosinophilia, and central bronchiectasis. The combination of structural changes and specific IgE supports the diagnosis.

Question 22Allergy

Which statement about the use of epinephrine in anaphylaxis during pregnancy is correct?

  1. Antihistamines should replace epinephrine
  2. Epinephrine should be given intramuscularly because maternal benefit outweighs fetal risk Correct answer.
  3. Epinephrine is contraindicated in pregnancy
  4. Only intravenous epinephrine should be used

Explanation

Intramuscular epinephrine is the treatment of choice for anaphylaxis in pregnancy because untreated anaphylaxis poses greater risk to both mother and fetus than the medication. Antihistamines are not a substitute.

Question 23Allergy

A patient develops recurrent angioedema without urticaria and has a family history of similar episodes. Which finding would most support hereditary angioedema?

  1. Elevated serum tryptase during attacks
  2. Positive skin prick test to foods
  3. High total IgE
  4. Low C4 with low or dysfunctional C1 inhibitor Correct answer.

Explanation

Hereditary angioedema results from C1 inhibitor deficiency or dysfunction, leading to complement activation and chronically low C4. It is bradykinin-mediated and not associated with urticaria or IgE.

Question 24Allergy

A patient with venom allergy is considering immunotherapy. Which statement about venom immunotherapy is most accurate?

  1. It is ineffective for preventing anaphylaxis
  2. It is contraindicated in all adults with cardiovascular disease
  3. It substantially reduces the risk of future systemic sting reactions Correct answer.
  4. It requires lifelong weekly injections

Explanation

Venom immunotherapy effectively reduces the risk of systemic reactions to future stings and is indicated for patients with systemic sting reactions and sensitization. Maintenance intervals are extended over time rather than weekly lifelong.

Question 25Allergy

Which of the following best explains why oral immunotherapy for food allergy requires careful dosing and observation?

  1. It has no risk of adverse reactions
  2. It permanently cures food allergy after the first dose
  3. Dosing can provoke allergic reactions including anaphylaxis, so escalation must be supervised Correct answer.
  4. It works by suppressing all IgE production

Explanation

Oral immunotherapy involves controlled exposure to an allergen and can trigger reactions during dosing and escalation, so it requires supervision and preparedness for anaphylaxis. It is not a guaranteed cure.

Question 26Allergy

A 30-year-old woman develops urticaria, angioedema, and hypotension minutes after receiving a penicillin injection. After stabilization, which laboratory test is most appropriate to confirm the diagnosis?

  1. Serum tryptase level Correct answer.
  2. Erythrocyte sedimentation rate
  3. Total serum IgE level
  4. Skin prick test to penicillin

Explanation

An elevated serum tryptase obtained within a few hours of anaphylaxis supports mast cell activation and is the standard confirmatory test. Skin testing for penicillin is used to evaluate IgE-mediated allergy but is not the primary test to confirm anaphylaxis. Total IgE and ESR are nonspecific and do not confirm the diagnosis.

Question 27Allergy

Which primary mediator is responsible for the immediate symptoms of allergic rhinitis?

  1. Platelet-activating factor
  2. Histamine Correct answer.
  3. Interleukin-5
  4. Leukotriene B4

Explanation

Histamine released from mast cells is the principal mediator of the immediate phase of allergic rhinitis, causing sneezing, itching, and rhinorrhea. Leukotrienes and interleukins contribute more to the late-phase response. Platelet-activating factor is involved in anaphylaxis and inflammation but is not the primary mediator of immediate rhinitis symptoms.

Question 28Allergy

A patient with chronic spontaneous urticaria has been on standard doses of a second-generation H1 antihistamine for 4 weeks with persistent symptoms. According to current guidelines, what is the next step?

  1. Add a leukotriene receptor antagonist
  2. Switch to a first-generation antihistamine
  3. Increase the antihistamine dose up to fourfold Correct answer.
  4. Start a short course of oral corticosteroids

Explanation

Guidelines recommend increasing the dose of a second-generation H1 antihistamine up to four times the standard dose if symptoms persist after 2–4 weeks. Adding a leukotriene antagonist or corticosteroids is reserved for refractory cases. First-generation antihistamines are not preferred due to sedating effects.

Question 29Allergy

Which statement about the mechanism of action of omalizumab in chronic spontaneous urticaria is most accurate?

  1. It depletes B cells via anti-CD20 activity
  2. It directly inhibits histamine release from mast cells
  3. It blocks H1 histamine receptors
  4. It binds free IgE and reduces IgE receptor expression on mast cells Correct answer.

Explanation

Omalizumab is a monoclonal antibody that binds free IgE, preventing it from engaging FcεRI on mast cells and basophils, and downregulates FcεRI expression. It does not directly inhibit histamine release or block histamine receptors. It is not an anti-CD20 agent.

Question 30Allergy

A 25-year-old man has a history of anaphylaxis to peanuts. He accidentally ingests peanuts and develops stridor and hypotension. He has no epinephrine autoinjector. What is the most appropriate immediate action?

  1. Administer intramuscular epinephrine 0.3 mg into the vastus lateralis Correct answer.
  2. Give oral diphenhydramine 50 mg
  3. Give inhaled albuterol via nebulizer
  4. Administer subcutaneous epinephrine 0.3 mg into the deltoid

Explanation

Intramuscular epinephrine into the vastus lateralis is the first-line treatment for anaphylaxis. Oral antihistamines and inhaled bronchodilators are adjuncts and do not reverse hypotension or airway edema. Subcutaneous administration is less reliable than intramuscular.

Question 31Allergy

Which of the following is the most common cause of anaphylaxis in children?

  1. Latex
  2. Foods Correct answer.
  3. Insect stings
  4. Medications

Explanation

Foods are the leading cause of anaphylaxis in children, with common triggers including peanuts, tree nuts, milk, and eggs. Insect stings and medications are more common triggers in adults. Latex is a less frequent cause overall.

Question 32Allergy

A patient with allergic rhinitis is not controlled on an intranasal corticosteroid. Which of the following is the most appropriate add-on therapy?

  1. Intranasal saline irrigation
  2. Oral decongestant
  3. Intranasal antihistamine Correct answer.
  4. Oral corticosteroid

Explanation

Adding an intranasal antihistamine to an intranasal corticosteroid is recommended for patients with inadequate response. Oral decongestants are not first-line for allergic rhinitis and have side effects. Saline irrigation is adjunctive but not as effective as adding an intranasal antihistamine. Oral corticosteroids are reserved for severe cases and short courses.

Question 33Allergy

Which of the following best describes the mechanism of action of montelukast in allergic rhinitis?

  1. It reduces IgE production by B cells
  2. It is a potent H1 antihistamine
  3. It blocks cysteinyl leukotriene receptors Correct answer.
  4. It inhibits histamine release from mast cells

Explanation

Montelukast is a leukotriene receptor antagonist that blocks cysteinyl leukotriene receptors, reducing leukotriene-mediated inflammation. It does not inhibit histamine release or act as an antihistamine. It does not directly reduce IgE production.

Question 34Allergy

A 40-year-old woman has recurrent episodes of angioedema without urticaria, abdominal pain, and a family history of similar symptoms. Which laboratory finding is most consistent with hereditary angioedema?

  1. Low C4 with normal C1 inhibitor level and function
  2. Low C4 with low C1 inhibitor level Correct answer.
  3. Elevated serum tryptase during attacks
  4. Elevated C1 inhibitor level

Explanation

Hereditary angioedema is most commonly caused by C1 inhibitor deficiency, leading to low C4 and low C1 inhibitor levels. A normal C1 inhibitor level with low C4 can occur in the less common type II HAE with dysfunctional C1 inhibitor, but low C1 inhibitor level is typical of type I. Elevated tryptase is seen in mast cell activation disorders, not HAE.

Question 35Allergy

Which of the following is the most appropriate treatment for an acute attack of hereditary angioedema?

  1. Oral prednisone
  2. C1 inhibitor concentrate Correct answer.
  3. Epinephrine intramuscularly
  4. Intravenous diphenhydramine

Explanation

C1 inhibitor concentrate is a first-line therapy for acute HAE attacks. Epinephrine, corticosteroids, and antihistamines are ineffective because the mechanism is bradykinin-mediated, not histamine-mediated.

Question 36Allergy

A patient with a history of anaphylaxis to a bee sting is being considered for venom immunotherapy. Which statement about venom immunotherapy is most accurate?

  1. It requires lifelong weekly maintenance injections
  2. It is contraindicated in patients with a history of anaphylaxis
  3. It reduces the risk of future systemic reactions by inducing immunologic tolerance Correct answer.
  4. It is effective only for yellow jacket venom

Explanation

Venom immunotherapy induces tolerance and significantly reduces the risk of systemic reactions to future stings. It is indicated for patients with a history of anaphylaxis and positive testing. It is effective for various Hymenoptera venoms, and maintenance dosing is typically every 4–8 weeks, not weekly.

Question 37Allergy

A 6-year-old child has a history of wheezing and hives after eating eggs. Egg-specific IgE is 10 kUA/L. Which of the following is the most appropriate next step?

  1. Prescribe an epinephrine autoinjector and advise strict avoidance Correct answer.
  2. Perform an oral food challenge to confirm the diagnosis
  3. Repeat the IgE test in 6 months
  4. Start oral immunotherapy immediately

Explanation

A history of immediate symptoms after ingestion with a high egg-specific IgE is highly predictive of egg allergy, so the diagnosis is confirmed and management includes avoidance and an epinephrine autoinjector. An oral food challenge is not necessary when the history and test are strongly positive. Oral immunotherapy is not the first step, and repeating IgE is not needed.

Question 38Allergy

Which of the following is the most appropriate recommendation for a patient with a history of systemic anaphylaxis to a specific food?

  1. Take a daily oral antihistamine to prevent reactions
  2. Avoid all outdoor activities
  3. Use a medical alert bracelet as the primary preventive measure
  4. Carry an epinephrine autoinjector at all times Correct answer.

Explanation

The cornerstone of management for food allergy anaphylaxis risk is strict avoidance and immediate access to epinephrine autoinjector. Daily antihistamines do not prevent anaphylaxis. Avoiding outdoor activities is not necessary, and a medical alert bracelet is adjunctive but not primary prevention.

Question 39Allergy

A patient with chronic rhinosinusitis and asthma is found to have peripheral eosinophilia and elevated IgE. Which additional finding would most suggest allergic bronchopulmonary aspergillosis (ABPA)?

  1. Elevated sweat chloride
  2. Central bronchiectasis on chest CT Correct answer.
  3. Low serum complement levels
  4. Positive antineutrophil cytoplasmic antibodies

Explanation

ABPA is characterized by central bronchiectasis, eosinophilia, elevated IgE, and Aspergillus sensitization. ANCA positivity suggests vasculitis. Low complement suggests immune complex disease. Elevated sweat chloride suggests cystic fibrosis.

Question 40Allergy

A 12-year-old boy has a history of allergic rhinitis and asthma. He develops hives and wheezing after playing soccer in the grass. Which of the following is the most likely trigger?

  1. Cockroach allergen
  2. Grass pollen Correct answer.
  3. Cat dander
  4. Dust mites

Explanation

Symptoms triggered by outdoor activities, especially in grass, suggest grass pollen allergy. Dust mites and cockroach allergens are indoors. Cat dander is associated with indoor exposure to cats.

Question 41Allergy

Which of the following is the most appropriate initial treatment for mild intermittent allergic rhinitis symptoms?

  1. Oral second-generation antihistamine Correct answer.
  2. Intranasal corticosteroid
  3. Allergen immunotherapy
  4. Oral decongestant

Explanation

For mild intermittent symptoms, an oral or intranasal second-generation antihistamine is appropriate first-line therapy. Intranasal corticosteroids are preferred for moderate-to-severe or persistent symptoms. Oral decongestants are not first-line, and immunotherapy is considered for more severe disease.

Question 42Allergy

Which of the following best describes the mechanism of action of omalizumab in allergic asthma?

  1. It is a long-acting beta-agonist
  2. It inhibits eosinophil migration
  3. It binds to IgE and prevents it from binding to mast cells Correct answer.
  4. It blocks leukotriene receptors

Explanation

Omalizumab is a monoclonal antibody that binds free IgE, preventing it from binding to high-affinity receptors on mast cells and basophils. It does not block leukotriene receptors or act as a bronchodilator. It indirectly reduces eosinophilic inflammation but is not a direct inhibitor of eosinophil migration.

Question 43Allergy

A patient with chronic urticaria is found to have high levels of anti-thyroid peroxidase antibodies. Which of the following is the most appropriate interpretation?

  1. It suggests an underlying lymphoma
  2. This is a common association and does not change management Correct answer.
  3. It confirms autoimmune thyroid disease as the cause of urticaria
  4. It indicates the need for thyroidectomy

Explanation

Anti-thyroid antibodies are common in chronic spontaneous urticaria and are not necessarily indicative of thyroid dysfunction requiring treatment. They do not confirm causality or require thyroidectomy. Lymphoma is not suggested by this finding.

Question 44Allergy

Which of the following is the most appropriate treatment for a patient with chronic rhinosinusitis with nasal polyps who has not responded to intranasal corticosteroids?

  1. Oral corticosteroids for a short course Correct answer.
  2. Long-term oral antibiotics
  3. Oral antihistamine
  4. Intranasal decongestant spray

Explanation

A short course of oral corticosteroids can reduce polyp size and symptoms in chronic rhinosinusitis with nasal polyps. Long-term antibiotics are not recommended. Decongestant sprays can cause rebound congestion. Oral antihistamines are not effective for polyps.

Question 45Allergy

Which of the following best explains why skin prick testing is preferred over intradermal testing for the initial evaluation of inhalant allergy?

  1. Skin prick testing is more sensitive than intradermal testing
  2. Intradermal testing is not affected by antihistamines
  3. Skin prick testing requires a longer wait time
  4. Intradermal testing has a higher risk of systemic reactions and is less specific Correct answer.

Explanation

Intradermal testing is more sensitive but less specific and carries a higher risk of systemic reactions, so it is not used for initial inhalant allergy evaluation. Skin prick testing is safer and adequately sensitive. Both are affected by antihistamines.

Question 46Allergy

Which immunoglobulin class is responsible for mediating type I immediate hypersensitivity reactions?

  1. IgG
  2. IgE Correct answer.
  3. IgM
  4. IgA

Explanation

Type I reactions are mediated by allergen-specific IgE bound to the high-affinity FcεRI receptor on mast cells and basophils. Cross-linking of this IgE by allergen triggers degranulation and release of histamine and other mediators.

Question 47Allergy

A patient reports that their allergic rhinitis symptoms are worst in spring and coincide with tree pollen. Which cell type is the primary source of histamine during the early-phase response?

  1. T lymphocytes
  2. Mast cells Correct answer.
  3. Neutrophils
  4. Eosinophils

Explanation

Mast cells located in the nasal mucosa are the principal source of preformed histamine that is released within minutes of allergen exposure. Eosinophils dominate the later-phase response rather than the immediate early-phase histamine surge.

Question 48Allergy

Which medication class is considered first-line pharmacologic therapy for mild intermittent allergic rhinitis?

  1. Second-generation oral antihistamines Correct answer.
  2. Intranasal cromolyn
  3. Intranasal corticosteroids
  4. Oral decongestants

Explanation

Second-generation oral H1 antihistamines are effective, well tolerated, and recommended as first-line therapy for mild or intermittent allergic rhinitis. Intranasal corticosteroids are preferred when symptoms are more persistent or moderate to severe.

Question 49Allergy

Which laboratory finding is most characteristic of atopic individuals when interpreting allergy testing?

  1. Reduced peripheral eosinophils
  2. Positive antinuclear antibodies
  3. Low serum tryptase
  4. Elevated total serum IgE Correct answer.

Explanation

Atopic individuals commonly have elevated total serum IgE, reflecting a generalized predisposition to IgE-mediated sensitization. However, total IgE alone is neither sensitive nor specific enough to diagnose clinical allergy, so specific testing is required.

Question 50Allergy

Which symptom pattern most strongly suggests a diagnosis of allergic rhinitis rather than infectious rhinitis?

  1. Unilateral nasal obstruction with facial pain
  2. Symptoms that resolve completely within 48 hours
  3. Symptoms that worsen seasonally and are accompanied by itchy eyes Correct answer.
  4. Purulent nasal discharge with fever

Explanation

Seasonal or perennial symptoms with prominent ocular itching and sneezing are hallmarks of IgE-mediated allergic rhinitis. Infectious rhinitis more often produces purulent discharge and fever and lacks the allergic ocular component.