Nokea
Dendritic cells play a role in:
- A. Costimulation of naïve T cells
- B. Processing of protein antigens to generate peptides
- C. Presentation of peptide-MHC complexes for recognition by T cell receptors
- D. All of the above
Correct Answer: D
Rationale: Dendritic cells play a crucial role in the immune system. Firstly, they provide costimulation to activate naïve T cells (A). Secondly, they process protein antigens into peptides for antigen presentation (B). Finally, dendritic cells present peptide-MHC complexes to T cell receptors for immune response activation (C). Therefore, the correct answer is D, as dendritic cells are involved in all these processes essential for initiating and regulating immune responses. Choices A, B, and C are incorrect as they are individual roles of dendritic cells and do not encompass the full range of functions that dendritic cells perform.
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In LN naïve T cells and activated dendritic cells interact in the
- A. Subcapsular sinus
- B. Cortex
- C. Paracortex
- D. Medulla
Correct Answer: C
Rationale: The correct answer is C: Paracortex. Naïve T cells circulate through the blood and lymphatic system until they encounter antigens presented by activated dendritic cells in the paracortex of lymph nodes. The paracortex is the region where T cell activation and proliferation occur, leading to an immune response. The subcapsular sinus (A) is primarily involved in filtering lymph fluid, the cortex (B) contains B cell follicles, and the medulla (D) contains plasma cells and macrophages. Thus, the paracortex is the specific site of interaction between naïve T cells and activated dendritic cells in lymph nodes.
A protective response to Leishmania parasites is most likely to occur when:
- A. Activated Th cells differentiate into Th1 effectors that secrete IL-4 required to induce secretion of appropriate antibody isotypes
- B. Activated Th cells differentiate into Th2 effectors that secrete IL-4 required to activate macrophages
- C. Activated Th cells differentiate into Th1 effectors that secrete IFNγ required to activate macrophages
- D. Either a Th1- or a Th2-mediated response occurs
Correct Answer: C
Rationale: The correct answer is C because in response to Leishmania parasites, the activation of Th cells into Th1 effectors that secrete IFNγ is crucial for activating macrophages to eliminate the intracellular parasites. IFNγ enhances the microbicidal activity of macrophages, helping to control the infection.
Choice A is incorrect because IL-4 is not required to induce the appropriate antibody response against Leishmania parasites.
Choice B is incorrect because Th2 effectors secreting IL-4 would not activate macrophages effectively against Leishmania, which is an intracellular pathogen.
Choice D is incorrect because in the case of Leishmania, a Th1-mediated response is most effective due to the need for macrophage activation by IFNγ.
The nurse is reviewing the immune system prior to discussing the actions with a patient. What type of cell should the nurse identify that is involved in cell-mediated immunity and has a cytotoxic action on tumor cells?
- A. Lysosomes
- B. Memory cells
- C. Natural killer cells
- D. Histocompatibility cells
Correct Answer: C
Rationale: The correct answer is C: Natural killer cells. Natural killer cells are involved in cell-mediated immunity and have cytotoxic actions on tumor cells. They are part of the innate immune system and can directly kill infected or cancerous cells. Lysosomes (A) are organelles within cells that break down waste materials. Memory cells (B) are a type of immune cell that "remembers" previous infections to mount a faster response upon re-exposure. Histocompatibility cells (D) are involved in recognizing self from non-self in transplant situations, not in cytotoxic actions on tumor cells.
Lymph consists of fluid that:
- A. Is taken up from tissues by lymphatic capillaries
- B. Carries antigens and mature dendritic cells to lymph nodes
- C. Is secreted by lymphocytes
- D. Two of these options are correct
Correct Answer: D
Rationale: Rationale:
1. A is correct as lymph is taken up from tissues by lymphatic capillaries.
2. B is correct as lymph carries antigens and mature dendritic cells to lymph nodes.
3. C is incorrect as lymph is not secreted by lymphocytes.
4. Therefore, D is correct as both A and B accurately describe the components and functions of lymph.
PRRs able to activate NFκB include
- A. TLR4
- B. NOD1
- C. NLRP3
- D. Both A and B
Correct Answer: D
Rationale: The correct answer is D because both TLR4 and NOD1 are pattern recognition receptors (PRRs) that can activate the NF-κB pathway. TLR4 recognizes bacterial lipopolysaccharides, while NOD1 detects bacterial peptidoglycan fragments. NLRP3, choice C, is an inflammasome receptor that activates caspase-1, not NF-κB. Therefore, choices A, B, and C are incorrect as they do not directly activate NF-κB like TLR4 and NOD1.