Nokea
What discovery is attributed to Elie Metchnikoff?
- A. Antitoxins
- B. Phagocytosis
- C. Germ theory of disease
- D. Smallpox eradication
Correct Answer: B
Rationale: The correct answer is B: Phagocytosis. Elie Metchnikoff is credited with discovering phagocytosis, the process in which certain cells engulf and digest foreign particles or microorganisms. He observed this phenomenon in starfish larvae, leading to a groundbreaking understanding of how immune cells defend the body against pathogens.
Choice A (Antitoxins) is incorrect because although Metchnikoff made contributions to immunology, his notable discovery was phagocytosis, not antitoxins. Choice C (Germ theory of disease) is incorrect as this theory was developed by Louis Pasteur and Robert Koch. Choice D (Smallpox eradication) is incorrect as this achievement is primarily attributed to the efforts of Edward Jenner and the World Health Organization.
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What happens to B cells after clonal selection and expansion?
- A. They produce cytokines
- B. They differentiate into plasma cells to produce antibodies
- C. They initiate phagocytosis
- D. They present antigens to T cells
Correct Answer: B
Rationale: After clonal selection and expansion, B cells differentiate into plasma cells to produce antibodies. This is crucial for the immune response as plasma cells are specialized in antibody production. B cells do not produce cytokines (choice A), initiate phagocytosis (choice C), or present antigens to T cells (choice D) post-clonal selection. Plasma cell differentiation is the key outcome of the B cell activation process, enabling the body to mount an effective immune response against pathogens.
Rolling' of neutrophils on endothelial cells is mediated by:
- A. Selectins expressed on endothelial cells
- B. Integrins expressed on leukocytes
- C. Chemokines such as CXCL-8 (IL-8)
- D. TNF
Correct Answer: A
Rationale: The correct answer is A: Selectins expressed on endothelial cells. Rolling of neutrophils on endothelial cells is a crucial step in the process of inflammation and immune response. Selectins are cell adhesion molecules expressed on endothelial cells that facilitate the initial interaction between leukocytes (such as neutrophils) and endothelial cells. This interaction allows for the rolling of neutrophils along the endothelial surface, which is essential for the subsequent steps of adhesion and transmigration into the tissues. Integrins (Choice B) are involved in the firm adhesion of leukocytes to endothelial cells, not in the initial rolling process. Chemokines (Choice C) such as CXCL-8 are signaling molecules that help in the recruitment of leukocytes but do not directly mediate the rolling process. TNF (Choice D) is a pro-inflammatory cytokine but is not directly involved in the rolling of neutrophils on endothelial cells.
What is the key characteristic of adaptive immunity compared to innate immunity?
- A. It uses physical barriers like skin
- B. It has antigen-specific responses and memory
- C. It responds to all antigens non-specifically
- D. It is faster than innate immunity
Correct Answer: B
Rationale: The correct answer is B because adaptive immunity is characterized by antigen-specific responses and memory. This means that it can recognize and target specific antigens upon exposure and develop long-lasting immunological memory.
Choice A is incorrect because physical barriers like skin are part of innate immunity, not adaptive immunity. Choice C is incorrect as adaptive immunity responds to specific antigens, not all antigens non-specifically. Choice D is incorrect because adaptive immunity typically takes longer to respond compared to innate immunity due to the need for activation and clonal expansion of specific immune cells.
Therapy for autoimmune diseases does NOT include
- A. Immuno-suppressive drugs such as cortisone
- B. Aspirin
- C. Anti-TNF therapy
- D. Anti-CD20
Correct Answer: E
Rationale: Rationale for Correct Answer (E):
E: Surgery is the correct answer. Surgery is not typically used as a primary therapy for autoimmune diseases. Autoimmune diseases are usually treated with medications such as immuno-suppressive drugs (A), anti-inflammatory drugs (B), and targeted therapies like anti-TNF (C) and anti-CD20 (D) to manage symptoms and control the immune response. Surgery is only considered in specific cases when other treatments have failed or for complications related to the autoimmune disease. Therefore, surgery is not a standard therapy for autoimmune diseases.
Summary of Incorrect Choices:
A: Immuno-suppressive drugs like cortisone are commonly used in autoimmune disease treatment.
B: Aspirin is an anti-inflammatory drug that can help manage symptoms in some autoimmune diseases.
C: Anti-TNF therapy targets specific molecules involved in the immune response in autoimmune diseases.
D: Anti-CD20 therapy targets B cells to modulate the immune response in autoimmune diseases.
Select the wrong statement concerning TLR4
- A. TLR4 is expressed on dendritic cells and macrophages
- B. It represents an example of a phagocytic receptor
- C. It is expressed on the membrane in complex with a protein called MD2
- D. Mice resistant to endotoxic shock harbor a mutation of TLR4
Correct Answer: B
Rationale: The correct answer is B because TLR4 is not a phagocytic receptor, but rather a pattern recognition receptor involved in recognizing pathogen-associated molecular patterns (PAMPs).
A: Correct, TLR4 is expressed on dendritic cells and macrophages.
C: Correct, TLR4 is expressed on the membrane in complex with MD2.
D: Correct, mice resistant to endotoxic shock have a mutation in TLR4, indicating its role in the immune response to endotoxins.