Nokea
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.
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Carpal tunnel syndrome (CTS) is caused when the carpal tunnel compresses which location?
- A. Radial artery
- B. Brachial artery
- C. Median nerve
- D. Ulnar nerve
Correct Answer: C
Rationale: The correct answer is C: Median nerve. Carpal tunnel syndrome occurs when the median nerve is compressed within the carpal tunnel in the wrist. This compression leads to symptoms like numbness, tingling, and weakness in the hand and fingers. The other choices are incorrect because the radial artery (A) and the brachial artery (B) are blood vessels, not nerves. The ulnar nerve (D) runs along a different path in the arm and is not involved in carpal tunnel syndrome.
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.
What triggers the release of mediators from mast cells during Type I hypersensitivity?
- A. Cross-linking of IgE molecules on the mast cell surface
- B. Activation of complement proteins
- C. Binding of IgG to antigen
- D. Phagocytosis of allergens
Correct Answer: A
Rationale: The correct answer is A. Cross-linking of IgE molecules on the mast cell surface triggers the release of mediators during Type I hypersensitivity. When allergens bind to IgE antibodies on mast cells, it leads to cross-linking of IgE molecules, causing the mast cell to release histamine and other inflammatory mediators. This process initiates the allergic response.
Explanation for incorrect choices:
B: Activation of complement proteins does not directly trigger mast cell degranulation in Type I hypersensitivity.
C: Binding of IgG to antigen is characteristic of Type II and Type III hypersensitivity reactions, not Type I.
D: Phagocytosis of allergens does not directly stimulate mast cells to release mediators in Type I hypersensitivity.
A patient with a genetic mutation of BRCA1 and a family history of breast cancer is admitted to the surgical unit where she is scheduled that day for a bilateral simple mastectomy. What is the reason for this procedure?
- A. Prevent breast cancer
- B. Diagnose breast cancer
- C. Cure or control breast cancer
- D. Provide palliative care for untreated breast cancer
Correct Answer: A
Rationale: A bilateral simple mastectomy is performed to prevent breast cancer in high-risk individuals with BRCA1 mutations.
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.