Nokea
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.
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An allogenic hematopoietic stem cell transplant is considered as treatment for a patient with acute myelogenous leukemia. What information should the nurse include when teaching the patient about this procedure?
- A. There is no risk for graft-versus-host disease because the donated marrow is treated to remove cancer cells
- B. The patient’s bone marrow will be removed,treated stored and then reinfused after intensive chemotherapy
- C. Peripheral stem cells are obtained from a donor who has a human leukocyte antigen (HLA) match with the patient
- D. There is no need for posttransplant protective isolation because the stem cells are infused directly into the blood
Correct Answer: C
Rationale: Peripheral stem cells from an HLA-matched donor are used in allogenic transplants.
What is NOT true about innate immunity?
- A. Innate cells are immediately active, do not need clonal amplification or differentiation
- B. Innate cells can respond better and faster at a second encounter with the same pathogen
- C. Innate receptors recognizing pathogens do not have a fine specificity but rather recognize structures broadly found in different microbes
- D. Innate receptors can also recognize modified-self
Correct Answer: B
Rationale: The correct answer is B because innate immune cells do not respond better and faster at a second encounter with the same pathogen. This is a characteristic of adaptive immunity, not innate immunity. During a second encounter, adaptive immune cells produce a faster and stronger response due to memory cells formed during the initial exposure. In contrast, innate immune cells do not have memory cells and their response remains the same upon repeated encounters. Choice A is correct as innate cells are immediately active and do not require clonal amplification or differentiation. Choice C is correct as innate receptors recognize broad structures on pathogens. Choice D is correct as innate receptors can recognize modified-self, such as in autoimmune diseases.
The basic structure of an antibody molecule is
- A. One light chain and one heavy chain that are covalently linked and form one antigen binding site
- B. Two identical heavy chains and two identical light chains that are covalently linked and form two antigen binding sites
- C. Two identical heavy chains and two identical light chains covalently linked to form one antigen binding site
- D. Two identical light chains that form the antigen binding site and two identical heavy chains that mediate the effector functions of antibodies
Correct Answer: B
Rationale: Rationale for Answer B:
1. Antibody structure consists of two identical heavy chains and two identical light chains.
2. These chains are covalently linked to form the Y-shaped structure of an antibody.
3. Each chain contributes to the formation of antigen-binding sites.
4. Therefore, two identical heavy chains and two identical light chains form two antigen-binding sites.
Summary of Incorrect Choices:
A: Incorrect because it describes only one antigen-binding site formed by one light chain and one heavy chain.
C: Incorrect because it describes one antigen-binding site formed by two identical heavy chains and two identical light chains.
D: Incorrect because it incorrectly describes the roles of light and heavy chains in antibody structure.
What is the typical outcome of a C1q deficiency in the complement system?
- A. Enhanced inflammation
- B. Reduced phagocytosis
- C. Autoimmune diseases such as SLE
- D. Increased cancer risk
Correct Answer: C
Rationale: The correct answer is C: Autoimmune diseases such as SLE. C1q is essential for the classical pathway of the complement system, which plays a crucial role in clearing immune complexes. A deficiency in C1q can lead to impaired immune complex clearance, resulting in the development of autoimmune diseases like Systemic Lupus Erythematosus (SLE).
Choice A (Enhanced inflammation) is incorrect because a deficiency in C1q would actually lead to decreased inflammation due to impaired complement activation.
Choice B (Reduced phagocytosis) is incorrect because phagocytosis is primarily mediated by the alternative pathway of the complement system, not the classical pathway involving C1q.
Choice D (Increased cancer risk) is incorrect as C1q deficiency is not directly associated with an increased risk of cancer.
The patient has received a bone marrow transplant. Soon after the transplant there is a rash on the patient’s skin. She says her skin is itchy and she has severe abdominal pain. What best summarizes what is happening to the patient and how she will be treated?
- A. Graft rejection occurring; treat with different immunosuppressive agents
- B. Dry skin and nausea are side effects of immunosuppresants; decrease the dose
- C. Transplanted bone marrow is rejecting her tissue; prevent with immunosuppressive agents
- D. Dry skin from the dry air and nausea from the food in the hospital; treat with humidifier and home food
Correct Answer: C
Rationale: The patient is likely experiencing graft-versus-host disease (GVHD), where transplanted cells attack the host tissue. This is treated with immunosuppressive agents.