Nokea
Which of the following is considered a defining characteristic of a TH2 response?
- A. Production of IgM antibodies
- B. Activation of CTL
- C. Recruitment and activation of neutrophils
- D. Production of IgE antibodies
Correct Answer: D
Rationale: The correct answer is D: Production of IgE antibodies. A TH2 response is characterized by the production of IgE antibodies, which are essential in allergic reactions. IgM antibodies (A) are produced during the primary immune response. Activation of CTL (B) is associated with a TH1 response. Neutrophils (C) are primarily involved in the innate immune response and are not specific to TH2 responses. In summary, the production of IgE antibodies is a defining characteristic of a TH2 response, distinguishing it from other immune responses.
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Identify the following types of cells that do HIV preferentially infect.
- A. Memory cells
- B. Helper T cells
- C. Cytotoxic T cells
- D. Natural killer cells
Correct Answer: B
Rationale: The correct answer is B: Helper T cells. HIV preferentially infects Helper T cells because they express the CD4 receptor, which serves as the primary binding site for the virus. Once infected, HIV impairs the Helper T cells' function, leading to immune system dysfunction. Memory cells (A), Cytotoxic T cells (C), and Natural killer cells (D) are not the primary targets of HIV infection as they do not express the CD4 receptor necessary for HIV entry and replication. Helper T cells are crucial for orchestrating immune responses, making them the primary target for HIV infection.
What is the significance of isotype switching in B cells?
- A. It enables the production of IgM only
- B. It enhances antibody affinity for antigens
- C. It changes the constant region to produce different antibody isotypes
- D. It eliminates antigen-specific B cells
Correct Answer: C
Rationale: Isotype switching in B cells involves changing the constant region to produce different antibody isotypes, such as IgG, IgA, or IgE. This is important for diversifying the functions of antibodies without altering antigen specificity. It allows for different effector functions, such as opsonization, neutralization, or complement activation. This process does not eliminate antigen-specific B cells, as it maintains the immunological memory. Isotype switching does not directly affect antibody affinity for antigens, which is primarily determined by somatic hypermutation and affinity maturation. It is not limited to producing IgM only, as B cells can switch to other isotypes based on the cytokine microenvironment.
What stimulates aldosterone secretion from the adrenal cortex?
- A. Excessive water intake
- B. Increased serum osmolality
- C. Decreased serum potassium
- D. Decreased sodium and water
Correct Answer: D
Rationale: Aldosterone secretion is stimulated by decreased sodium and water levels (renin-angiotensin-aldosterone system activation) and low blood pressure.
Which rationale describes treatment of atopic allergies with immunotherapy?
- A. It decreases the levels of allergen-specific T helper cells.
- B. It decreases the level of IgE so that it does not react as readily with an allergen.
- C. It stimulates increased IgG to bind with allergen-reactive sites, preventing mast cell-bound IgE reactions.
- D. It gradually increases the amount of allergen in the body until it is no longer recognized as foreign and does not elicit an antibody reaction.
Correct Answer: C
Rationale: Immunotherapy stimulates the production of blocking IgG antibodies, which compete with IgE for allergen-binding sites, preventing mast cell activation.
Which immunoglobulin is responsible for the primary immune response and forms antibodies to ABO blood antigens?
- A. IgA
- B. IgD
- C. IgG
- D. IgM
Correct Answer: D
Rationale: IgM is the first antibody produced in the primary immune response and plays a key role in responding to blood group antigens.