Mcq_sem3_mini1 - Hypersensitivity
Questions and Answers
- 1.
Leprosy is a chronic infectious disease caused by Mycobacterium leprae. The ability of this organism to cause disease is related to it’s ability to infect, persist in, and replicate within macrophages. The lepromin skin test is used to determine what type of leprosy a person has. In this test, inactivated Mycobacterium leprae organisms are injected just beneath the skin. At the site of injection, a person with a positive test will develop an area of induration with erythema peaking around 48 hours after the injection. If this test measures a hypersens4tivity reaction against the organism, what type of hypersensitivity reaction is it intended to detect?
- A.
Type I
- B.
Type IV
- C.
Type II
- D.
Type U or 111
- E.
Type III
Correct Answer
B. Type IVExplanation
The lepromin skin test is intended to detect a Type IV hypersensitivity reaction. Type IV hypersensitivity, also known as delayed-type hypersensitivity, is characterized by the activation of T cells and the release of cytokines, resulting in inflammation at the site of antigen exposure. In the case of the lepromin skin test, the injection of inactivated Mycobacterium leprae organisms triggers a delayed hypersensitivity reaction in individuals with leprosy, leading to the development of induration and erythema at the injection site.Rate this question:
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- 2.
The principle difference between type II and type III hypersensitivity is:
- A.
The class (isotype of antibody)
- B.
Whether the antibody reacts with the antigen on the cell or reacts with antigen before it interacts with the cell
- C.
The participation of complement
- D.
The participation of T cells
Correct Answer
B. Whether the antibody reacts with the antigen on the cell or reacts with antigen before it interacts with the cellExplanation
Type II hypersensitivity occurs when antibodies bind to antigens on the surface of cells, leading to cell destruction. In contrast, type III hypersensitivity occurs when antibodies form immune complexes with soluble antigens before they interact with cells. The difference lies in the location of the antibody-antigen interaction. Type II hypersensitivity involves direct binding to cell surface antigens, while type III hypersensitivity involves the formation of immune complexes in the bloodstream. The participation of complement and T cells can occur in both type II and type III hypersensitivity reactions, but it is not the defining difference between the two types.Rate this question:
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- 3.
A child stung by a bee experiences respiratory distress within minutes and lapses into unconsciousness. This reaction is probably mediated by:
- A.
IgE antibody
- B.
IgG antibody
- C.
Sensitized T cells
- D.
Complement
- E.
IgM antibody
Correct Answer
A. IgE antibodyExplanation
The correct answer is IgE antibody. When a child is stung by a bee, the body may produce IgE antibodies in response to the bee venom. These antibodies bind to mast cells and basophils, triggering the release of inflammatory mediators such as histamine. This can cause respiratory distress and unconsciousness. IgE antibodies are known to play a crucial role in allergic reactions, including those caused by insect stings.Rate this question:
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- 4.
A patient with severe asthma gets no relief from antihistamines. The symptoms are MOST likely to be caused by:
- A.
IL-2
- B.
Leukotrienes
- C.
Serotonin
- D.
Bradykinin
Correct Answer
B. LeukotrienesExplanation
Leukotrienes are lipid mediators that play a key role in the inflammatory response, particularly in asthma. In severe asthma, the airways become inflamed and constricted, leading to symptoms such as wheezing, shortness of breath, and coughing. Antihistamines primarily target histamine, which is involved in allergic reactions, but they do not effectively reduce the inflammation caused by leukotrienes. Therefore, if a patient with severe asthma does not experience relief from antihistamines, it is likely because their symptoms are primarily caused by leukotrienes.Rate this question:
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- 5.
Hypersensitivity to penicillin and hypersensitivity to poison oak are both:
- A.
Mediated by IgE antibody
- B.
Mediated by IgG and IgM antibody
- C.
Intiated by haptens
- D.
Initiated by Th2 cells
Correct Answer
C. Intiated by haptensExplanation
Hypersensitivity to penicillin and hypersensitivity to poison oak are both initiated by haptens. Haptens are small molecules that can bind to larger molecules in the body, forming a complex that triggers an immune response. In the case of penicillin, the hapten is the penicillin molecule itself, which can bind to proteins in the body and cause an allergic reaction. Similarly, in the case of poison oak, the hapten is a chemical called urushiol, which is found in the plant and can bind to proteins in the skin, leading to an allergic reaction.Rate this question:
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- 6.
Your patient has been treated for endocarditis with Penicillin G for the past 2 weeks. She now has fever and maculopapular erythematous rash over her chest and abdomen. A urinalysis shows significant protein in the urine. If the fever, rash and proteinuria are immunologic in origin, which one of the following is MOST likely to be involved?
- A.
IgG and complement
- B.
IgE and histamine
- C.
IL-2 and cytotoxic T cells
- D.
Gamma interferon and macrophages
Correct Answer
A. IgG and complementExplanation
The patient's symptoms of fever, rash, and proteinuria suggest an immunologic reaction. IgG and complement are most likely to be involved in this reaction. IgG is an antibody that is produced in response to an infection or inflammation, and complement is a group of proteins that helps to activate the immune response. Together, IgG and complement can cause inflammation and tissue damage, leading to the symptoms seen in the patient.Rate this question:
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- 7.
A child disturbs a wasp nest, is stung repeatedly, and goes into shock within minutes, manifesting respiratory failure and vascular collapse. This is MOST likely due to;
- A.
Systemic anaphylaxis
- B.
Serum sickness
- C.
An Arthus reaction
- D.
Cytotoxic hypersensitivity
Correct Answer
A. Systemic anapHylaxisExplanation
The child's symptoms of respiratory failure and vascular collapse within minutes after being stung repeatedly by wasps suggest a severe and immediate allergic reaction, known as systemic anaphylaxis. Systemic anaphylaxis occurs when the immune system overreacts to an allergen, such as the wasp venom, causing widespread release of histamine and other chemicals that lead to respiratory distress and low blood pressure. This is the most likely explanation for the child's symptoms in this scenario.Rate this question:
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- 8.
A delayed hypersensitivity reaction is characterized by:
- A.
Edema without a cellular infiltrate
- B.
An infiltrate composed of neutrophiis
- C.
An infiltrate composed of helper T cells and macrophages
- D.
An infiltrate composed of eosinophits
Correct Answer
C. An infiltrate composed of helper T cells and macropHagesExplanation
A delayed hypersensitivity reaction is characterized by an infiltrate composed of helper T cells and macrophages. This type of reaction occurs several hours to days after exposure to an antigen and involves the activation of T cells. Helper T cells release cytokines that attract macrophages to the site of inflammation. Macrophages then phagocytose the antigen and release additional inflammatory mediators, leading to tissue damage. This type of reaction is commonly seen in conditions such as contact dermatitis and tuberculin skin testing.Rate this question:
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- 9.
Regarding anaphylactic (type I) and immune complex (type III) hypersensitivities, which of the following is the MOST accurate?
- A.
IgE is involved in both anaphylactic and immune complex hypersensitivibes
- B.
Complement is involved in both anaphylactic and immune complex hypersensitivities
- C.
Less antigen is typically needed to trigger and anaphylactic reaction than an immune complex reaction
- D.
Neutrophils play more important role in anaphylactic reactions than in immune complex reactions
Correct Answer
C. Less antigen is typically needed to trigger and anapHylactic reaction than an immune complex reactionExplanation
In anaphylactic hypersensitivity, IgE antibodies are involved in the immune response, leading to the release of inflammatory mediators such as histamine. This type of hypersensitivity is characterized by a rapid and severe allergic reaction. On the other hand, immune complex hypersensitivity involves the formation of antigen-antibody complexes that deposit in tissues, leading to inflammation and tissue damage. Complement proteins are involved in the activation of the immune response in both types of hypersensitivity. However, the statement that less antigen is typically needed to trigger an anaphylactic reaction than an immune complex reaction is the most accurate. Anaphylactic reactions can occur with minimal exposure to allergens, while immune complex reactions generally require a higher antigen load.Rate this question:
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- 10.
A patient was undergoing a series of surgical procedures requiring general anesthetic. At the third procedure he suddenly became hypotensive with marked cardiac arrhythmia. In addition his breathmg became difficuft due to extensive bronchocorstriction and obstructive laryngeal edema. Despite the efforts of the surgical team the patient developed severe and permanent brain damage due to hypoxernia. It was subsequently discovered that the patient had developed IgG antibodies to the anesthetic gas and this had resulted in an anaphylactoid response to the anesthetic. What type of reaction caused this condition?
- A.
Type I Hypersensitivity
- B.
Type II Hypersensitivity
- C.
Type III Hypersensitivity
- D.
Type IV Hypersensitivity
- E.
Direct activation of mast cells by the anesthetic gas
Correct Answer
C. Type III HypersensitivityExplanation
The patient's symptoms, including hypotension, cardiac arrhythmia, bronchoconstriction, and laryngeal edema, indicate a systemic allergic reaction known as anaphylactoid response. The development of IgG antibodies to the anesthetic gas suggests an immune-mediated response. Type III hypersensitivity is characterized by the formation of immune complexes that deposit in tissues, leading to inflammation and tissue damage. This aligns with the patient's severe brain damage due to hypoxernia. Therefore, the correct answer is Type III Hypersensitivity.Rate this question:
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- 11.
In Henoch-Schonlein purpura, what is the reason for the purpuric rash?
- A.
Bacteria that adhere to vascular walls inducing necrosis
- B.
IgM immune complexes that induce vasculitis
- C.
Immune-mediated destruction of bacteria, releasing endotoxin
- D.
The disease is a the result of superantigen activity by the infectious agent
- E.
IgA immune complexes that induce vasculitis
Correct Answer
E. IgA immune complexes that induce vasculitisExplanation
In Henoch-Schonlein purpura, the purpuric rash is caused by IgA immune complexes that induce vasculitis. Henoch-Schonlein purpura is a type of vasculitis characterized by inflammation of the blood vessels. In this condition, IgA immune complexes deposit in the blood vessel walls, leading to an inflammatory response and damage to the vessels. This results in the development of a purpuric rash, which is characterized by small purple spots on the skin caused by bleeding under the skin.Rate this question:
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- 12.
A 44-year-old man is given an intramuscular high dose of peniciffln. About 8 days later, he develops chills, fever and a rash, If his symptoms are due to an immune reaction to the drug, what type of reaction is this considered?
- A.
Type I Hypersensitivity reaction
- B.
Type I Hypersensitivity reaction
- C.
Type IV Hypersensitivity reaction
- D.
Anaphylactoid reaction
- E.
Type III Hypersensitivity reaction
Correct Answer
E. Type III Hypersensitivity reactionExplanation
Type III hypersensitivity reactions occur when immune complexes form in the bloodstream and deposit in various tissues, leading to inflammation and tissue damage. Symptoms typically occur days to weeks after exposure to the antigen. In this case, the symptoms of chills, fever, and rash developing 8 days after receiving the penicillin injection suggest a delayed immune reaction, which is characteristic of a type III hypersensitivity reaction.Rate this question:
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Aug 18, 2023Quiz Edited by
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Apr 06, 2012Quiz Created by
Rossstudent
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