What is the consequence of granzyme entering a target cell?
- A. Neutralization of toxins
- B. Activation of apoptosis pathways
- C. Inhibition of cytokine secretion
- D. Promotion of antigen presentation
Correct Answer: B
Rationale: Granzyme entering a target cell activates apoptosis pathways by inducing cell death. Firstly, granzyme activates caspases leading to cell death. Secondly, it triggers DNA fragmentation and cell shrinkage. Lastly, it enhances membrane blebbing and apoptotic body formation. The other choices are incorrect because granzyme does not neutralize toxins, inhibit cytokine secretion, or promote antigen presentation within a target cell.
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After engagement of its pattern recognition receptors what happens to a dendritic cell to enable its role in naïve T cell activation?
- A. Expression of MHC class I molecules begins
- B. Increased uptake of antigens
- C. Expression of the B7 molecule
- D. PAMP-induced proliferation
Correct Answer: C
Rationale: After engagement of pattern recognition receptors, dendritic cells upregulate expression of the B7 molecule, which is essential for co-stimulation of naïve T cells. This step is crucial for activating T cells. MHC class I molecules present antigens to CD8+ T cells, not CD4+ T cells, so choice A is incorrect. Dendritic cells already have high antigen uptake ability, so choice B is not directly related to activation. PAMP-induced proliferation is not a typical response of dendritic cells after pattern recognition receptor engagement, making choice D incorrect.
In immune response mechanism clonal selection is a process in which:
- A. a special type of clone cell line is identified in a cell culture
- B. the proliferation and differentiation of lymphocytes occur in response to a specific antigen
- C. cloning of a specific gene is done by inserting the same into a bacteria by recombinant DNA technology
- D. selection of an appropriate cell type is done for the purpose of cloning
Correct Answer: B
Rationale: The correct answer is B because in immune response mechanism, clonal selection refers to the process where lymphocytes (T and B cells) proliferate and differentiate in response to a specific antigen. This process ensures that the immune system can effectively target and eliminate pathogens.
Option A is incorrect because clonal selection does not refer to identifying a specific type of clone cell line in cell culture.
Option C is incorrect because clonal selection does not involve cloning a specific gene by inserting it into bacteria using recombinant DNA technology.
Option D is incorrect because clonal selection is not about selecting an appropriate cell type for cloning purposes.
In summary, the correct answer, option B, best describes the process of clonal selection in the context of the immune response mechanism.
If the BCR of a developing cell has no binding affinity for self-antigens in the bone marrow the B cell will be:
- A. Clonally deleted
- B. Anergized
- C. A possible cause of autoimmunity in the periphery
- D. Allowed to mature and enter the periphery
Correct Answer: D
Rationale: The correct answer is D: Allowed to mature and enter the periphery. In this scenario, since the developing B cell has no binding affinity for self-antigens in the bone marrow, it will not undergo clonal deletion or anergy. Therefore, it will be allowed to mature and enter the periphery where it can encounter foreign antigens and participate in the immune response. Choices A and B are incorrect because clonal deletion and anergy are mechanisms used to eliminate or inactivate self-reactive B cells to prevent autoimmunity. Choice C is incorrect because a B cell without self-binding affinity is not a cause of autoimmunity in the periphery.
Which of the following statements is NOT true?
- A. B cells are important in the defense against extracellular pathogens
- B. The number of memory B cells recognizing antigen X is always smaller than the number of naïve B cells recognizing antigen X, as most specific B cells are killed when the immune response subsides
- C. Memory B cells are B cells differentiated from cells that have encountered the antigen and are long-lived
- D. The B cell repertoire is virtually infinite and includes specificities for any possible antigen
Correct Answer: B
Rationale: The correct answer is B because the statement is false. Memory B cells are formed during an immune response and persist long-term, allowing for a faster and more robust response upon reinfection with the same antigen. The number of memory B cells recognizing an antigen is typically greater than the number of naïve B cells, as they are specifically primed and preserved. In contrast, naïve B cells are naive to the antigen and need to undergo activation and differentiation upon encountering the antigen for the first time. Therefore, statement B is incorrect as it inaccurately suggests that memory B cells are always fewer than naïve B cells recognizing the same antigen.
Therapy for autoimmune diseases does NOT include
- A. Immuno-suppressive drugs such as cortisone
- B. Aspirin
- C. Anti-TNF therapy
- D. Anti-CD20
Correct Answer: E
Rationale: Rationale for Correct Answer (E):
E: Surgery is the correct answer. Surgery is not typically used as a primary therapy for autoimmune diseases. Autoimmune diseases are usually treated with medications such as immuno-suppressive drugs (A), anti-inflammatory drugs (B), and targeted therapies like anti-TNF (C) and anti-CD20 (D) to manage symptoms and control the immune response. Surgery is only considered in specific cases when other treatments have failed or for complications related to the autoimmune disease. Therefore, surgery is not a standard therapy for autoimmune diseases.
Summary of Incorrect Choices:
A: Immuno-suppressive drugs like cortisone are commonly used in autoimmune disease treatment.
B: Aspirin is an anti-inflammatory drug that can help manage symptoms in some autoimmune diseases.
C: Anti-TNF therapy targets specific molecules involved in the immune response in autoimmune diseases.
D: Anti-CD20 therapy targets B cells to modulate the immune response in autoimmune diseases.