Nokea
What treatment is commonly used for anaphylaxis?
- A. Antihistamines only
- B. Epinephrine
- C. Corticosteroids only
- D. Antibiotics
Correct Answer: B
Rationale: The correct answer is B: Epinephrine. Epinephrine is the first-line treatment for anaphylaxis as it rapidly reverses the symptoms by constricting blood vessels, relaxing airway muscles, and increasing heart rate. It is crucial in preventing severe complications and can be life-saving. Antihistamines (choice A) only target histamine effects, which are not sufficient in managing anaphylaxis. Corticosteroids (choice C) are used as adjunct therapy but are not as immediate or critical as epinephrine. Antibiotics (choice D) are not indicated for anaphylaxis treatment. Therefore, epinephrine is the most appropriate choice for managing anaphylaxis effectively.
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Which of the following is the best match between antibody class and major antibody effector function?
- A. IgG: Opsonization
- B. IgA: Complement activation
- C. IgE: Antibody-dependent cell-mediated cytotoxicity
- D. IgM: Neonatal immunity
Correct Answer: A
Rationale: The correct answer is A: IgG: Opsonization. IgG antibodies are known for their role in opsonization, where they tag pathogens for phagocytosis by immune cells. This process enhances the removal of pathogens. IgA is mainly involved in mucosal immunity and not complement activation, making choice B incorrect. IgE is associated with allergic reactions and not antibody-dependent cell-mediated cytotoxicity as stated in choice C. IgM is the first antibody produced in response to an infection and plays a role in neonatal immunity, making choice D incorrect.
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.
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.
A 69-year-old woman asks the nurse whether it is possible to 'catch' cancer because many of her friends of the same age have been diagnosed with different kinds of cancer. In responding to the woman, the nurse understands that what factor increases the incidence of tumors in older adults?
- A. An increase in autoantibodies
- B. Decreased activity of the bone marrow
- C. Decreased differentiation of T lymphocytes
- D. Decreased size and activity of the thymus gland
Correct Answer: D
Rationale: The thymus gland shrinks with age, reducing the production of new T cells, which impairs immune surveillance and increases cancer risk.
T cells can recognize
- A. Linear peptides
- B. The shape of antigens
- C. Buried epitopes
- D. Soluble antigens
Correct Answer: B
Rationale: The correct answer is B: The shape of antigens. T cells recognize antigens based on their shape, specifically the conformational structure of the antigen. T cell receptors interact with the surface of antigens, forming a complex based on the shape complementarity. This interaction is crucial for T cell activation and immune response.
A: Linear peptides - While T cells can recognize linear peptides presented by MHC molecules, the primary mode of recognition is through the shape of antigens.
C: Buried epitopes - T cells typically recognize epitopes displayed on the surface of antigens rather than buried within the structure.
D: Soluble antigens - T cells can recognize both soluble and membrane-bound antigens, but the key factor is the shape rather than the solubility of the antigen.