Nokea
Which of the following cells are 'professional' antigen presenting cells
- A. Neutrophils, dendritic cells, B cells
- B. B cells, T cells, dendritic cells
- C. Macrophages, B cells, dendritic cells
- D. Neutrophils, epithelial cells, dendritic cells
Correct Answer: C
Rationale: The correct answer is C: Macrophages, B cells, dendritic cells. Professional antigen-presenting cells are specialized immune cells that effectively present antigens to T cells. Macrophages, B cells, and dendritic cells are considered professional APCs because they express major histocompatibility complex (MHC) molecules and co-stimulatory molecules, allowing them to effectively activate T cells. Neutrophils and epithelial cells are not considered professional APCs as they have limited ability to present antigens to T cells. B cells and T cells are not APCs themselves, but B cells can act as APCs when they present antigens to T cells in the context of an immune response.
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What is Louis Pasteur's main contribution to immunology?
- A. Development of the smallpox vaccine
- B. Discovery of phagocytosis
- C. Germ theory of disease and vaccine development
- D. Theory of innate immunity
Correct Answer: C
Rationale: Louis Pasteur's main contribution to immunology is the germ theory of disease and vaccine development. Firstly, Pasteur's germ theory revolutionized our understanding of infectious diseases by demonstrating that microorganisms are the cause. Secondly, he developed the concept of vaccination by creating vaccines for diseases such as rabies and anthrax, laying the foundation for modern immunology. The other choices are incorrect because:
A: Pasteur worked on the rabies vaccine, not the smallpox vaccine.
B: Phagocytosis was discovered by Metchnikoff, not Pasteur.
D: Pasteur did not propose the theory of innate immunity.
Which of the following is NOT true about a potential vaccine that induces a strong cytotoxic T cell response to influenza virus but failed to induce neutralizing antibodies:
- A. It would not prevent actual infection
- B. It would lessen the severity of disease
- C. It may be more cross-protective against different variants of influenza virus
- D. It would result in failure to clear the virus
Correct Answer: D
Rationale: The correct answer is D because a strong cytotoxic T cell response can still effectively clear the virus even without neutralizing antibodies. Cytotoxic T cells directly kill infected cells, helping to control and eliminate the virus. Therefore, the vaccine would not result in failure to clear the virus.
A) Incorrect: While the vaccine may not prevent infection, the presence of cytotoxic T cells would help in controlling and reducing the severity of the infection.
B) Incorrect: The vaccine may indeed lessen the severity of the disease by aiding in the clearance of infected cells.
C) Incorrect: A strong T cell response can provide broader protection against different variants of the virus.
All of the following can be a consequence of the formation of NETS with the exception of:
- A. Killing of microbes contained in phagolysosomes
- B. Death of neutrophils
- C. Trapping of microbes at sites of infection
- D. Extracellular microbial killing
Correct Answer: A
Rationale: The correct answer is A because NETs (Neutrophil Extracellular Traps) are released by neutrophils to trap and kill microbes extracellularly. Step 1: NETs are composed of DNA, histones, and antimicrobial proteins. Step 2: They trap microbes at the site of infection. Step 3: The antimicrobial proteins in NETs kill the trapped microbes. Step 4: Neutrophils themselves do not contain microbes inside phagolysosomes, so the killing of microbes contained in phagolysosomes is not a direct consequence of NET formation. Therefore, choice A is the exception. Choices B, C, and D are incorrect as they are all consequences of NET formation.
"Hamburger disease" is caused by
- A. Helicobacter pylori
- B. Salmonella typhimurium
- C. A strain of E. coli
- D. Shigella flexneri
Correct Answer: C
Rationale: The correct answer is C: A strain of E. coli. "Hamburger disease" is commonly caused by E. coli O157:H7, a strain of Escherichia coli bacteria found in undercooked ground beef. This strain can lead to severe foodborne illness. Helicobacter pylori (Choice A) is associated with stomach ulcers, not hamburger disease. Salmonella typhimurium (Choice B) and Shigella flexneri (Choice D) are both known to cause food poisoning, but they are not typically linked to hamburger disease specifically. In this case, the unique association between E. coli O157:H7 and undercooked ground beef makes Choice C the correct answer.
A patient is taking diuretic drugs that cause sodium loss from the kidney. Which fluid or electrolyte imbalance is most likely to occur in this patient?
- A. Hyperkalemia
- B. Hyponatremia
- C. Hypocalcemia
- D. Hypotonic fluid loss
Correct Answer: B
Rationale: Diuretics promote sodium excretion, leading to hyponatremia as more water follows sodium out of the body.