Nokea
Which of the following molecular interactions mediate signal 2 during activation of naïve T cells
- A. L-Selectin/PNAD
- B. CD4/MHC II or CD8/MHC I
- C. TCR/MHC I or TCR/MHC II
- D. TCR/CD3
Correct Answer: E
Rationale: I'm sorry, but there seems to be a mistake in the question as the correct answer is not listed among the choices provided. Please provide the correct options or the correct answer so I can give you the detailed explanation you are looking for.
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During an acute inflammatory response which of the following is the first event
- A. Extravasation of neutrophils
- B. Upregulation of endothelial adhesion molecules
- C. Secretion of opsonins
- D. Phagocytosis
Correct Answer: B
Rationale: The correct answer is B because upregulation of endothelial adhesion molecules is the first event during an acute inflammatory response. This event facilitates the initial recruitment of leukocytes, including neutrophils, to the site of inflammation. Extravasation of neutrophils (choice A) occurs after adhesion molecules are upregulated. Secretion of opsonins (choice C) and phagocytosis (choice D) occur later in the inflammatory response process after the neutrophils have been recruited to the site of inflammation.
Epithelial cells at mucosal sites have barrier functions exerted through several mechanisms. These mechanisms do not include:
- A. Secretion of mucins
- B. Secretion of antimicrobial peptides
- C. Phagocytosis of microbes
- D. Tight junctions
Correct Answer: C
Rationale: The correct answer is C: Phagocytosis of microbes. Epithelial cells primarily act as a physical barrier to prevent the entry of microbes. Phagocytosis is a function of immune cells, not epithelial cells. A: Secretion of mucins helps trap pathogens. B: Secretion of antimicrobial peptides aids in defense. D: Tight junctions form a physical barrier between cells. Therefore, phagocytosis is not a direct mechanism exerted by epithelial cells at mucosal sites.
What type of receptor is found on B cells for antigen recognition?
- A. T cell receptor (TCR)
- B. B cell receptor (BCR)
- C. Fc receptor
- D. Complement receptor
Correct Answer: B
Rationale: The correct answer is B because B cells express B cell receptors (BCR) on their surface for recognizing antigens. BCRs consist of immunoglobulin molecules that bind specifically to antigens. T cell receptors (A) are found on T cells, not B cells. Fc receptors (C) bind to the Fc region of antibodies, while complement receptors (D) recognize complement proteins, not antigens. Therefore, the BCR is the specific receptor on B cells for antigen recognition.
Choose the best definition for effector T cells. They are cells that
- A. Have never seen their specific antigen
- B. Have just seen their specific antigen and start to proliferate
- C. Have been energized
- D. Have been activated, expanded and are able to kill or help other cells
Correct Answer: D
Rationale: Effector T cells are fully activated, expanded, and capable of carrying out their functions, such as killing infected cells or assisting in immune responses. The correct choice (D) accurately describes the characteristics of effector T cells. They are not naïve cells (A), as they have encountered their specific antigen. They are not just starting to proliferate (B), as they have already undergone extensive proliferation. They have not only been energized (C), but have also completed the necessary steps for full activation and functionality.
The current Influenza vaccine includes
- A. 3 type A strains
- B. A combination of one H1N1, one H5N1 and a B strain
- C. Only 2009 H1N1
- D. Only the most common seasonal H1N1 strain
Correct Answer: B
Rationale: Step 1: The current Influenza vaccine is designed to provide protection against multiple strains to increase effectiveness.
Step 2: Option B includes a combination of different strains (H1N1, H5N1, and B), covering a broader spectrum of the virus.
Step 3: Including different strains helps to address potential mutations and variations in circulating viruses.
Step 4: Option B is the most comprehensive choice compared to others, offering a more robust protection against various strains.
Summary: Option A is too limited with only 3 type A strains, while option C focuses only on 2009 H1N1 strain. Option D is also limited to only the most common seasonal H1N1 strain. Option B stands out as the correct choice for its broad coverage of different strains.