Nokea
Which molecule is essential for antigen presentation to T cells?
- A. Antibody
- B. Major Histocompatibility Complex (MHC)
- C. Complement protein C3
- D. Cytokines
Correct Answer: B
Rationale: The correct answer is B: Major Histocompatibility Complex (MHC). MHC molecules present antigens to T cells for immune response activation. They bind to antigenic peptides and present them on the cell surface for recognition by T cells. This is crucial for the immune system to distinguish between self and non-self antigens. Antibodies (A) are produced by B cells and do not directly present antigens to T cells. Complement protein C3 (C) is involved in the complement system for immune defense, not antigen presentation. Cytokines (D) are signaling molecules that regulate immune responses but do not directly present antigens to T cells.
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One hypothesis links the cytokine storm associated with SARS and Avian Flu to
- A. Elevated levels of ROS during these infections in the lung
- B. Elevated levels of acute phase proteins
- C. Formation of the inflammasome through activation of NLRP3
- D. Recognition of oxidized forms of a host lipid called PAPC by TLR4
Correct Answer: E
Rationale: I'm sorry, but it seems like there might be a mistake in the question provided as there is no option E listed. Could you please provide the correct answer or clarify the question so that I can assist you further?
Crohn's disease is
- A. A chronic inflammatory disease caused by defective NFκB signaling
- B. Associated with mutations of NLRP3
- C. Associated with defective production of ROS
- D. A chronic inflammatory disease associated with overgrowth of gut commensal flora
Correct Answer: D
Rationale: Step-by-step rationale for why answer D is correct:
1. Crohn's disease is characterized by chronic inflammation in the gastrointestinal tract.
2. It is associated with dysregulation of the immune response to gut flora.
3. Overgrowth of gut commensal flora can trigger and exacerbate inflammation in Crohn's disease.
4. Choices A, B, and C do not directly relate to the pathophysiology of Crohn's disease, making them incorrect.
The type of immunological protection provided by plasma therapy is
- A. Natural active
- B. Natural passive
- C. Artificial active
- D. Artificial passive
Correct Answer: D
Rationale: The correct answer is D: Artificial passive. Plasma therapy involves administering preformed antibodies to provide immediate protection against a specific pathogen. This is considered artificial passive immunity because the antibodies are obtained from an external source rather than being produced by the individual's immune system.
Explanation:
1. Natural active immunity (Choice A) is when the body produces its antibodies after exposure to a pathogen, which is not the case in plasma therapy.
2. Natural passive immunity (Choice B) is when antibodies are passed from mother to fetus or through breast milk, not obtained through plasma therapy.
3. Artificial active immunity (Choice C) involves vaccination to stimulate the body's immune response, which is different from plasma therapy.
In summary, the correct answer is D (Artificial passive) because plasma therapy provides immediate immunity through externally sourced antibodies, distinguishing it from the other types of immunological protection.
Which of the following statements is NOT true
- A. T cells expressing CD4 exert their function mainly through secretion of cytokines
- B. CD8 T cells interact with MHC class I molecules on antigen presenting cells
- C. CD4 T cells can help B cells because B cells express MHC class II molecules and can present antigen to T cells
- D. CD3 is not necessary for TCR signaling in cytotoxic T cells
Correct Answer: D
Rationale: The correct answer is D because CD3 is indeed necessary for TCR signaling in cytotoxic T cells. CD3 is a crucial component of the T cell receptor (TCR) complex, which is responsible for initiating intracellular signaling upon recognition of antigen-MHC complexes. Without CD3, TCR signaling cannot occur, leading to impaired T cell activation and cytotoxic function. Choices A, B, and C are incorrect because they accurately describe the functions and interactions of T cells expressing CD4 and CD8 with antigen presenting cells, as well as the role of CD4 T cells in helping B cells through antigen presentation.
Which is not a PAMP?
- A. Viral dsRNA
- B. Peptidoglycan
- C. ROS
- D. Flagellin
Correct Answer: C
Rationale: The correct answer is C: ROS (Reactive Oxygen Species) is not a PAMP (Pathogen-Associated Molecular Pattern) because it is not a specific molecular pattern derived from pathogens. PAMPs are recognized by the innate immune system to trigger an immune response. Viral dsRNA, peptidoglycan, and flagellin are all examples of PAMPs as they are specific molecules commonly found in pathogens that can be recognized by pattern recognition receptors (PRRs) on immune cells, leading to activation of the immune response.ROS, on the other hand, are reactive molecules produced by host cells in response to pathogens but are not specific molecular patterns derived from pathogens. Therefore, ROS is not considered a PAMP.