Nokea
Which of the following statements is NOT true
- A. During T cell development the decision to become a CD4 or a CD8 positive cell is a random event
- B. During T cell differentiation the decision to become a TH1 or a TH2 cell CD4+ is a random event
- C. TH2 CD4+ cells secrete IL-4
- D. IL-10 is TH2 polarizing cytokine
Correct Answer: B
Rationale: The correct answer is B: During T cell differentiation, the decision to become a TH1 or a TH2 cell CD4+ is not a random event. This is because T cell differentiation into TH1 or TH2 cells is guided by specific signals from the environment, such as cytokines present during activation. TH1 cells are induced by IL-12 and IFN-gamma, while TH2 cells are induced by IL-4. This process is not random but rather a result of specific signaling cues.
A: During T cell development, the decision to become a CD4 or a CD8 positive cell is not a random event. It is determined by interactions with thymic stromal cells and the T cell receptor.
C: TH2 CD4+ cells do secrete IL-4, so this statement is true.
D: IL-10 is not a TH2 polarizing cytokine; rather, it is known to have regulatory functions in immune responses.
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What antibody mediates Type I hypersensitivity?
- A. IgA
- B. IgE
- C. IgG
- D. IgM
Correct Answer: B
Rationale: The correct answer is B: IgE. In Type I hypersensitivity reactions, IgE antibodies are involved. Firstly, upon initial exposure to an allergen, B cells produce IgE antibodies specific to that allergen. IgE antibodies then bind to mast cells and basophils. Upon subsequent exposure to the same allergen, it cross-links the IgE antibodies on mast cells and basophils, leading to degranulation and release of inflammatory mediators like histamine. This results in the symptoms of Type I hypersensitivity reactions.
Choice A (IgA) is incorrect because IgA is mainly involved in mucosal immunity. Choice C (IgG) is incorrect because while IgG can be involved in Type II and Type III hypersensitivity reactions, it is not the primary antibody in Type I hypersensitivity. Choice D (IgM) is incorrect because IgM is typically involved in the primary immune response, not in Type I hypersensitivity reactions.
Which of the following is NOT a common condition associated with Type I hypersensitivity?
- A. Asthma
- B. Food allergies
- C. Anaphylaxis
- D. Systemic lupus erythematosus (SLE)
Correct Answer: D
Rationale: The correct answer is D: Systemic lupus erythematosus (SLE). Type I hypersensitivity involves IgE-mediated reactions to allergens, leading to immediate responses like asthma, food allergies, and anaphylaxis. SLE is an autoimmune disease involving immune complexes and not IgE antibodies. Therefore, SLE is not directly associated with Type I hypersensitivity. Asthma, food allergies, and anaphylaxis are all examples of Type I hypersensitivity reactions due to IgE-mediated mechanisms.
Which of the following are considered desirable features for a Flu vaccine
- A. Induction of a neutralizing antibody response
- B. Induction of a cytotoxic T cell response
- C. Protection against multiple strains
- D. All of the above A, B and C
Correct Answer: D
Rationale: The correct answer is D, "All of the above A, B, and C".
Step 1: Induction of a neutralizing antibody response (A) is crucial as it helps prevent the virus from infecting cells.
Step 2: Induction of a cytotoxic T cell response (B) is important to eliminate infected cells and stop the spread of the virus.
Step 3: Protection against multiple strains (C) is desirable to ensure broad coverage against different flu strains.
Combining A, B, and C in a vaccine would provide comprehensive protection against the flu by targeting different aspects of the immune response. Choices A, B, and C are incorrect individually as they each address only one aspect of a desirable flu vaccine, whereas the correct answer D encompasses all three crucial features.
What type of cells do natural killer (NK) cells target?
- A. Bacterial cells
- B. Virus-infected and cancerous cells
- C. Plasma cells
- D. Self-antigens
Correct Answer: B
Rationale: Natural killer (NK) cells target virus-infected and cancerous cells because they have the ability to recognize abnormal cells through activating receptors. These cells can identify changes in surface markers associated with viral infection or cancer, leading to their destruction. NK cells do not target bacterial cells (choice A), plasma cells (choice C), or self-antigens (choice D) as these are not typically recognized as threats by the immune system. NK cells play a crucial role in immune surveillance against abnormal cells, making choice B the correct answer.
Match the immunoglobulins with their primary functions:
- A. 1-C, 2-A, 3-B, 4-D
- B. 1-B, 2-C, 3-D, 4-A
- C. 1-D, 2-B, 3-C, 4-A
- D. 1-A, 2-D, 3-B, 4-C
Correct Answer: A
Rationale: The correct answer is A: 1-C, 2-A, 3-B, 4-D. Immunoglobulins are antibodies with different functions:
1. IgG (C) - Main antibody in secondary immune response.
2. IgA (A) - Found in mucosal areas, neutralizes pathogens.
3. IgM (B) - First antibody produced in primary immune response.
4. IgE (D) - Involved in allergic reactions and defense against parasites. Other choices are incorrect as they mismatch the immunoglobulins with their functions.