Nokea
What is the primary trigger for NK cell activation?
- A. Presence of PAMPs
- B. Lack of normal self-surface structures
- C. High levels of complement proteins
- D. Antigen presentation by dendritic cells
Correct Answer: B
Rationale: The primary trigger for NK cell activation is the lack of normal self-surface structures. NK cells are part of the innate immune system and recognize cells with altered or missing self-antigens. This triggers their activation to eliminate these abnormal cells. Presence of PAMPs (A) activates other immune cells like macrophages. High levels of complement proteins (C) activate the complement cascade but do not directly trigger NK cell activation. Antigen presentation by dendritic cells (D) activates adaptive immune responses through T cells, not NK cells. Therefore, the correct answer is B as it directly relates to NK cell function.
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What are the two phases of Type I hypersensitivity?
- A. Early phase and latent phase
- B. Immediate phase and late phase
- C. Acute phase and chronic phase
- D. Primary phase and secondary phase
Correct Answer: B
Rationale: The correct answer is B: Immediate phase and late phase. In Type I hypersensitivity, the immediate phase occurs rapidly after exposure to an allergen, leading to the release of mediators like histamine. The late phase occurs several hours later, involving sustained inflammatory response.
A: Early phase and latent phase - Incorrect because the terms do not accurately describe the phases of Type I hypersensitivity.
C: Acute phase and chronic phase - Incorrect because Type I hypersensitivity does not typically progress to a chronic phase.
D: Primary phase and secondary phase - Incorrect as these terms are not commonly used to describe the phases of Type I hypersensitivity.
Which cells are responsible for antigen presentation to T cells?
- A. Plasma cells
- B. Antigen-presenting cells (APCs)
- C. NK cells
- D. Eosinophils
Correct Answer: B
Rationale: The correct answer is B: Antigen-presenting cells (APCs). APCs, such as dendritic cells, macrophages, and B cells, are specialized cells that capture, process, and present antigens to T cells to initiate an immune response. They express major histocompatibility complex (MHC) molecules for antigen presentation. Plasma cells (A) produce antibodies, NK cells (C) are involved in killing infected cells, and eosinophils (D) are primarily involved in parasitic infections and allergic responses, not antigen presentation to T cells.
Peyer's patches are found in the:
- A. Intestine
- B. Spleen
- C. Lungs
- D. Skin
Correct Answer: A
Rationale: Peyer's patches are lymphoid nodules located in the small intestine, specifically in the ileum. They play a crucial role in the immune response of the gut. The correct answer is A: Intestine because Peyer's patches are specifically found in the intestine. The other choices are incorrect because the spleen is a different organ involved in filtering blood, the lungs are primarily involved in respiration, and the skin is the body's largest organ responsible for protection and thermoregulation.
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.
The immunoglobulin Joining chain (J-chain) is
- A. only produced by T-Cells
- B. only produced by neutrophils
- C. associated with only multimeric forms of IgM and IgA
- D. associated with IgE for histamine release
Correct Answer: C
Rationale: Step-by-step rationale:
1. The J-chain is a polypeptide involved in the formation of polymeric IgM and IgA.
2. Polymeric forms of IgM and IgA contain the J-chain, aiding in their multimeric structure.
3. The J-chain is not exclusive to T-cells or neutrophils, making choices A and B incorrect.
4. IgE is associated with FcεRI receptors for histamine release, so choice D is incorrect.
Summary:
The correct answer is C because the J-chain is specifically associated with the multimeric forms of IgM and IgA, helping to form their structure. Choices A, B, and D are incorrect as the J-chain is not solely produced by T-cells, neutrophils, or associated with IgE for histamine release.