Nokea
T cells help B cells to:
- A. Undergo isotype switching
- B. Produce antibodies against protein antigens
- C. Receive signal 2 of activation
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." T cells help B cells undergo isotype switching by providing cytokines. They also help B cells produce antibodies against protein antigens by activating them. T cells provide signal 2 of activation to B cells through the interaction of CD40 on B cells with CD40L on T cells. Therefore, all of these functions are critical for the collaboration between T and B cells in the immune response.
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Which of the following concerned with Leishmania is NOT true
- A. Meditated by IgE
- B. Is a unicellular parasite
- C. Activation of macrophages is essential for killing the parasite
- D. Escapes host immune attack by hiding inside neutrophils
Correct Answer: a
Rationale: The correct answer is A: Mediated by IgE. Leishmania infection is not primarily mediated by IgE antibodies. The immune response against Leishmania involves T cells, macrophages, and cytokines. IgE is not a major player in the defense against Leishmania. Choices B, C, and D are incorrect because Leishmania is indeed a unicellular parasite, activation of macrophages is essential for killing the parasite, and Leishmania can hide inside neutrophils to escape the host immune attack.
Acute-phase proteins include
- A. Selectins
- B. Mannose binding lectin (MBL)
- C. Lysozyme
- D. Defensins
Correct Answer: B
Rationale: Step 1: Acute-phase proteins are a group of proteins produced by the liver in response to inflammation or infection.
Step 2: Mannose binding lectin (MBL) is an acute-phase protein that plays a role in the innate immune response.
Step 3: MBL binds to pathogens and activates the complement system to enhance immune responses.
Step 4: Selectins are cell adhesion molecules, not acute-phase proteins.
Step 5: Lysozyme is an enzyme that destroys bacterial cell walls, not typically classified as an acute-phase protein.
Step 6: Defensins are antimicrobial peptides, not typically classified as acute-phase proteins.
Summary:
MBL is the correct choice as it is a well-known acute-phase protein involved in the immune response. Selectins, Lysozyme, and Defensins are not typically classified as acute-phase proteins and are involved in different functions.
When assessing a patient for anaphylaxis, be alert for:
- A. Chest pain and indigestion.
- B. Hives and dyspnea.
- C. Hypertension and blurred vision.
- D. Headache and photophobia.
Correct Answer: B
Rationale: Anaphylaxis typically presents with symptoms such as hives (skin reaction) and dyspnea (difficulty breathing), which are indicative of an allergic response affecting the airways and skin. Hypertension and blurred vision are not typical signs of anaphylaxis.
During the adaptive immune response mature dendritic cells provide polarizing cytokines that influence the differentiation of Th subsets. The polarizing cytokine(s) produced by a dendritic cell depends on:
- A. Whether it expresses MHC class I or MHC class II molecules
- B. The type of pathogen it encounters
- C. Which type of Fc receptor it expresses
- D. All of the above are correct
Correct Answer: B
Rationale: The correct answer is B: The type of pathogen it encounters. Dendritic cells produce different polarizing cytokines based on the type of pathogen they encounter. This is crucial for directing the differentiation of T helper (Th) subsets. Choice A is incorrect because the expression of MHC class I or II molecules by dendritic cells is important for antigen presentation to T cells, not for determining polarizing cytokines. Choice C is also incorrect because Fc receptors are involved in antibody-mediated immune responses, not in determining polarizing cytokines. Therefore, the correct answer is B as it directly influences the differentiation of Th subsets by providing appropriate polarizing cytokines based on the encountered pathogen.
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.