Nokea
The nurse is studying hypersensitivity reactions. Which reactions are correctly matched with their hypersensitivity types? (Select one that does not apply.)
- A. Type I—examples include hay fever and anaphylaxis.
- B. Type II—mediated by action of immunoglobulin M (IgM).
- C. Type III—immune complex deposits in blood vessel walls.
- D. Type IV—examples are poison ivy and transplant rejection.
Correct Answer: B
Rationale: The correct answer is B because Type II hypersensitivity reactions are mediated by the action of immunoglobulin G (IgG) or immunoglobulin M (IgM), not just IgM alone. IgG or IgM antibodies target specific antigens on the surface of cells or tissues, leading to cell destruction. In contrast, Type I hypersensitivity reactions (choice A) involve immediate IgE-mediated responses to allergens like hay fever and anaphylaxis. Type III reactions (choice C) are characterized by immune complex deposition in tissues, not blood vessel walls. Type IV reactions (choice D) are delayed hypersensitivity reactions involving T cell-mediated responses, such as poison ivy contact dermatitis and transplant rejection.
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Why don't we have a successful HIV vaccine?
- A. The high mutation rate of HIV interferes with the generation of a protective memory response
- B. Because it is difficult to induce mucosal immunity that would block the sexual transmission of the virus
- C. Because HIV targets immune cells
- D. All of the above represent challenges for the creation of an effective HIV vaccine
Correct Answer: D
Rationale: The correct answer is D because all the statements in choices A, B, and C are valid reasons why we don't have a successful HIV vaccine.
A: HIV has a high mutation rate, making it challenging to generate a protective memory response.
B: Inducing mucosal immunity is difficult to block sexual transmission, a common route of HIV infection.
C: HIV targets immune cells, which hinders the immune system's ability to mount an effective response.
Therefore, all these factors combined pose significant challenges for creating an effective HIV vaccine.
Select incorrect mechanism for the development of autoimmune disorder.
- A. A second exposure to an allergen.
- B. Cross-reaction of antibodies formed against foreign antigens with self-antigens.
- C. Exposure of previously 'hidden' self-antigens to the adaptive immune system.
- D. Mutation followed by the appearance of membrane proteins not previously present.
Correct Answer: A
Rationale: The correct answer is A. A second exposure to an allergen does not lead to the development of autoimmune disorders. The key mechanisms involved in autoimmune disorders are self-tolerance breakdown and immune system attacking self-antigens.
Explanation:
1. B: Cross-reaction of antibodies formed against foreign antigens with self-antigens is a possible mechanism for autoimmune disorders.
2. C: Exposure of previously 'hidden' self-antigens to the adaptive immune system can trigger autoimmune responses.
3. D: Mutation followed by the appearance of membrane proteins not previously present can lead to autoimmune disorders, as the immune system may recognize these proteins as foreign.
Summary:
Choice A is incorrect because a second exposure to an allergen does not cause the immune system to target self-antigens, which is the hallmark of autoimmune disorders. Choices B, C, and D are more plausible mechanisms for the development of autoimmune disorders.
In mice, mutations of which of the following genes cause the 'scurfy' phenotype (scaly skin and multiple autoimmune disorders)?
- A. FOXP3
- B. AIRE
- C. NFkB
- D. IRF
Correct Answer: A
Rationale: Rationale:
1. FOXP3 gene encodes a transcription factor crucial for regulatory T cells function.
2. Mutations in FOXP3 lead to dysfunctional regulatory T cells, causing autoimmune disorders.
3. Scurfy phenotype matches the symptoms of autoimmune disorders seen with FOXP3 mutations.
Summary:
- B (AIRE): AIRE mutations cause autoimmune polyendocrine syndrome, not scurfy phenotype.
- C (NFkB): NFkB is a transcription factor involved in immune response but not linked to scurfy phenotype.
- D (IRF): IRF is a regulator of interferon signaling, not directly associated with scurfy phenotype.
What effect does the action of the complement system have on inflammation?
- A. Modifies the inflammatory response to prevent stimulation of pain
- B. Increases body temperature, resulting in destruction of microorganisms
- C. Produces prostaglandins and leukotrienes that increase blood flow, edema, and pain
- D. Increases inflammatory responses of vascular permeability, chemotaxis, and phagocytosis
Correct Answer: D
Rationale: The complement system enhances inflammation by increasing vascular permeability, attracting immune cells (chemotaxis), and promoting phagocytosis of pathogens or debris.
The interaction of a TCR with its specific antigen is denoted as "signal 1" of activation and does NOT need the contribution of which of the following components
- A. TCR α-chain
- B. TCR β-chain
- C. 28
- D. MHC molecule
Correct Answer: C
Rationale: Step-by-step rationale:
1. "Signal 1" activation requires TCR to interact with its specific antigen.
2. TCR consists of α and β chains, which are essential for antigen recognition.
3. MHC molecule is crucial for presenting antigens to TCR for recognition.
4. Choice C (28) is not a component involved in TCR-antigen interaction.
5. Therefore, the correct answer is C as it does not contribute to "signal 1" activation.
Summary:
A and B are incorrect as TCR α and β chains are necessary for antigen recognition.
D is incorrect as MHC molecule is essential for presenting antigens to TCR.
C is correct as it is not involved in the TCR-antigen interaction process.