Nokea
What are examples of type I or IgE-mediated hypersensitivity reactions (select all that apply)?
- A. Asthma
- B. Urticaria
- C. Angioedema
- D. Allergic rhinitis
Correct Answer: A
Rationale: Type I hypersensitivity reactions involve IgE-mediated responses, including asthma, urticaria, angioedema, and allergic rhinitis.
You may also like to solve these questions
naïve T cells can be found in
- A. Blood
- B. Germinal centers
- C. Mostly in the medullary region of lymph nodes (LN)
- D. In non-lymphoid tissues such as the skin
Correct Answer: A
Rationale: The correct answer is A: Blood. Naïve T cells are circulating in the blood, ready to encounter antigens. They can move to secondary lymphoid organs like lymph nodes. Germinal centers (B) are sites of B cell maturation, not where naïve T cells are primarily found. While some naïve T cells enter lymph nodes (C), they are not mostly located in the medullary region. Naïve T cells can also migrate to non-lymphoid tissues (D), but their primary residence is in the blood.
Which dietary change is most beneficial in reducing the risk of colorectal cancer?
- A. Increased fiber intake
- B. High-fat diet
- C. Reduced carbohydrate consumption
- D. Increased protein intake
Correct Answer: A
Rationale: Increased fiber intake promotes healthy digestion and reduces the risk of colorectal cancer.
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.
Dendritic cells migrating from tissues enter the lymph nodes through
- A. Thoracic duct
- B. HEV
- C. Afferent lymphatics
- D. Efferent lymphatics
Correct Answer: C
Rationale: The correct answer is C: Afferent lymphatics. Dendritic cells migrate from tissues to lymph nodes through afferent lymphatics, which are small vessels that carry lymph into the lymph nodes. Once inside the lymph nodes, dendritic cells interact with T cells to initiate immune responses. The thoracic duct (A) drains lymph from the entire body into the bloodstream, not directly into lymph nodes. High endothelial venules (HEV) (B) are specialized blood vessels in lymph nodes where lymphocytes enter from the bloodstream, not dendritic cells. Efferent lymphatics (D) carry lymph out of the lymph nodes, not into them.
The immunoglobulin class which is the least abundant in the normal adult is
- A. IgG
- B. IgA
- C. IgE
- D. IgD
Correct Answer: C
Rationale: The correct answer is C, IgE. IgE is the least abundant immunoglobulin in the normal adult because it is primarily involved in allergic responses and parasitic infections, leading to its lower baseline levels compared to other classes. IgG is the most abundant and provides long-term immunity. IgA is found in mucosal areas and secretions, crucial for local immunity. IgD functions primarily as a B cell receptor and its levels are relatively low in circulation. Therefore, IgE stands out as the least abundant in the normal adult due to its specialized role in immune responses.