Nokea
Autoimmune diseases are associated with several susceptibility factors. Environmental factors associated with increased risk of autoimmune disease include:
- A. Infections
- B. Level of exposure to the sun
- C. Imbalance of microbiota composition
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Autoimmune diseases have complex causes, involving genetic predisposition and environmental factors. Infections can trigger autoimmune responses, sunlight exposure can influence immune function, and an imbalance in microbiota composition can lead to dysregulated immune responses. Therefore, all three factors can contribute to an increased risk of autoimmune diseases. Choices A, B, and C individually are all associated with autoimmune diseases, making option D the correct choice.
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If HLA-DR4 is considered a 'risk' allele for disease 'X', this means:
- A. All individuals with the HLA-DR4 allele will get disease X
- B. All individuals with disease X have the HLA-DR4 allele
- C. An individual with the HLA-DR4 allele has an increased chance of developing disease X compared to other individuals
- D. All of the above are true
Correct Answer: C
Rationale: The correct answer is C because having the HLA-DR4 allele increases the likelihood of developing disease X but does not guarantee it. Choice A is incorrect because not all individuals with HLA-DR4 will get disease X. Choice B is incorrect because not all individuals with disease X have the HLA-DR4 allele. Choice D is incorrect because it falsely states that all statements are true, which is not the case.
Which of the following leukocytes is involved in antibody-dependent cell-mediated cytotoxicity?
- A. Natural Killer (NK) cells
- B. Neutrophils
- C. Macrophages
- D. Mast cells
Correct Answer: A
Rationale: The correct answer is A: Natural Killer (NK) cells. NK cells are involved in antibody-dependent cell-mediated cytotoxicity by recognizing target cells coated with antibodies and inducing their death. NK cells play a crucial role in immune surveillance and defense against infected or malignant cells. Neutrophils, macrophages, and mast cells are not directly involved in antibody-dependent cell-mediated cytotoxicity. Neutrophils are primarily responsible for phagocytosis, macrophages are antigen-presenting cells, and mast cells are involved in allergic reactions.
What is true about OPV (Oral Polio Vaccine)?
- A. Induces mainly an IgG response
- B. Is currently the method of choice because considered safer than IPV (Inactivated Polio Vaccine)
- C. Induces mucosal immunity that blocks enteric infection and viral transmission
- D. All of the above is true about OPV
Correct Answer: C
Rationale: The correct answer is C because OPV induces mucosal immunity that blocks enteric infection and viral transmission. This is crucial in preventing the spread of poliovirus through the fecal-oral route. Choice A is incorrect because OPV primarily induces an IgA response in the mucosal surfaces, not IgG. Choice B is incorrect because while OPV is effective, it carries a risk of vaccine-derived poliovirus, making IPV the preferred choice in some situations. Therefore, Choice C is the most accurate as it highlights the unique ability of OPV to induce mucosal immunity, which is essential for preventing poliovirus transmission.
What is required for sensitization in contact hypersensitivity?
- A. Antigen-antibody complex formation
- B. T cell presentation of a hapten-modified antigen
- C. Mast cell degranulation
- D. Cytokine suppression
Correct Answer: B
Rationale: The correct answer is B because sensitization in contact hypersensitivity requires T cell presentation of a hapten-modified antigen. This process activates T cells, leading to immune response. Antigen-antibody complex formation (A) is more related to immune responses in humoral immunity. Mast cell degranulation (C) is associated with allergic reactions, not contact hypersensitivity. Cytokine suppression (D) would hinder, not promote, the immune response needed for sensitization in contact hypersensitivity.
Which of the following causes memory cells to convert to plasma cells?
- A. An organ transplant
- B. Release of lymphokines
- C. Re-exposure to a specific antigen
- D. Initial exposure to an antigen
Correct Answer: C
Rationale: Memory cells convert to plasma cells upon re-exposure to a specific antigen which triggers a rapid and robust immune response.