Nokea
What cytokine is produced by Regulatory T cells to suppress immune responses?
- A. IL-2
- B. IL-10
- C. IFN-gamma
- D. TNF-alpha
Correct Answer: B
Rationale: The correct answer is B: IL-10. Regulatory T cells produce IL-10 to suppress immune responses by inhibiting the activation and function of other immune cells. IL-2 (A) is mainly produced by activated T cells to promote proliferation. IFN-gamma (C) is produced by T cells and NK cells to enhance immune response. TNF-alpha (D) is produced by macrophages and T cells to induce inflammation. IL-10 stands out as the suppressor cytokine in this context.
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Concerning with NLRs, which of the following is NOT correct
- A. Are cytosolic receptors for MAMPs and DAMPs
- B. Include NOD receptors
- C. In Drosophila also important for embryonic development
- D. Similar proteins are also found in plants
Correct Answer: C
Rationale: The correct answer is C because NLRs are not important for embryonic development in Drosophila. NLRs are primarily involved in immune responses by recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) in the cytosol. Choice A is correct as NLRs are indeed cytosolic receptors for MAMPs and DAMPs. Choice B is correct as NOD receptors are a subset of NLRs. Choice D is correct as similar proteins to NLRs are also found in plants, known as NBS-LRR proteins. Therefore, the incorrect statement is C, as NLRs are not essential for embryonic development in Drosophila.
What was Edward Jenner's major contribution to immunology?
- A. Discovering antibodies
- B. Proposing innate immunity theory
- C. Developing the smallpox vaccine
- D. Discovering the germ theory of disease
Correct Answer: C
Rationale: Edward Jenner's major contribution to immunology was developing the smallpox vaccine. He introduced the concept of vaccination by using cowpox to protect against smallpox. This marked the beginning of modern immunization. Discovering antibodies (A) and proposing innate immunity theory (B) were not directly attributed to Jenner. Discovering the germ theory of disease (D) was later proposed by Louis Pasteur and Robert Koch, not Jenner. Overall, choice C is correct as it aligns with Jenner's groundbreaking work in immunization.
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.
Which of the following enzymes removes 5' phosphate groups thereby preventing or decreasing the self-sealing of restricted plasmid vector molecules?
- A. Calf intestinal phosphatase
- B. Pyrophosphatase
- C. Phosphohydrolase
- D. phosphate exonuclease
Correct Answer: A
Rationale: The correct answer is A: Calf intestinal phosphatase. This enzyme removes 5' phosphate groups from DNA molecules, preventing self-ligation of restricted plasmid vectors. This step is crucial in generating linearized vectors for downstream applications. Pyrophosphatase (B) hydrolyzes pyrophosphate bonds, not 5' phosphate groups. Phosphohydrolase (C) is a general term for enzymes that hydrolyze phosphoester bonds, not specific to 5' phosphate removal. Phosphate exonuclease (D) degrades nucleic acids by removing nucleotides from the 3' end, not the 5' phosphate group.
T-cell antigen receptors are distinguished from antibodies by which of the following
- A. T-Cell receptors are glycosylated
- B. T-cell receptors must interact with antigen uniquely presented by other cells but not with free antigen
- C. T-Cell receptors bind various cytokines
- D. T-Cell receptors bind complement to lyse cells
Correct Answer: B
Rationale: The correct answer is B. T-cell receptors must interact with antigens uniquely presented by other cells but not with free antigen. This is because T-cell receptors recognize antigens that are processed and presented on the surface of other cells via major histocompatibility complex (MHC) molecules. T-cell receptors specifically bind to the antigen-MHC complex, allowing T-cells to respond to specific foreign antigens.
A: T-cell receptors are not distinguished from antibodies by glycosylation. Both T-cell receptors and antibodies can be glycosylated, so this does not differentiate them.
C: T-cell receptors do not bind various cytokines. Cytokine receptors are separate entities that mediate cellular responses to cytokines.
D: T-cell receptors do not bind complement to lyse cells. Complement activation is a separate immune response mechanism not involving T-cell receptors.