Nokea
Severe combined immunodeficiency (SCID) is a disease caused by:
- A. Infection with human immunodeficiency virus
- B. One of several inherited genetic mutations
- C. Deficiency of both innate and adaptive immune components
- D. Deficiency of hematopoietic stem cells
Correct Answer: B
Rationale: Step 1: SCID is a genetic disorder affecting the immune system.
Step 2: Inherited genetic mutations cause abnormalities in immune cells.
Step 3: These mutations lead to severe deficiencies in immune function.
Step 4: Choice B accurately reflects the genetic basis of SCID.
Summary: Choice A is incorrect because SCID is not caused by HIV. Choice C is incorrect as it oversimplifies the immune deficiencies in SCID. Choice D is incorrect because SCID primarily affects immune cells, not stem cells.
You may also like to solve these questions
Which type of hypersensitivity reaction occurs with rheumatoid arthritis and acute glomerulonephritis?
- A. Type I or IgE-mediated hypersensitivity reaction
- B. Type II or cytotoxic hypersensitivity reaction
- C. Type III or immune-complex mediated hypersensitivity reaction
- D. Type IV or delayed hypersensitivity reaction
Correct Answer: C
Rationale: Type III hypersensitivity involves immune complexes depositing in tissues, leading to inflammation, as seen in rheumatoid arthritis and acute glomerulonephritis.
A confirmatory lab test for HIV includes:
- A. Western blot.
- B. Low WBC.
- C. Comprehensive metabolic panel.
- D. Enzyme-linked immunosorbent assay (ELISA).
Correct Answer: A
Rationale: The Western blot test is considered the gold standard for confirming HIV infection after initial screening tests like ELISA. Low WBC and comprehensive metabolic panels are not specific to HIV diagnosis.
A cytokine essential for clonal expansion of T cells is
- A. IL-1
- B. IL-2
- C. IL4
- D. IL-5
Correct Answer: B
Rationale: The correct answer is B: IL-2. IL-2 is essential for the clonal expansion of T cells as it promotes T cell proliferation. It is produced by activated T cells themselves and plays a crucial role in regulating immune responses. IL-1 is involved in inflammation, not T cell expansion. IL-4 is important for Th2 cell differentiation, while IL-5 is critical for eosinophil activation. In summary, IL-2 specifically promotes T cell clonal expansion, making it the correct choice in this context.
Virulence factors can be transferred from pathogenic to non-pathogenic bacterial strains that are part of the normal flora. An example of a commensal bacterial species that has turned into a pathogenic strain is:
- A. E. coli 0157:H7
- B. M. tuberculosis
- C. Group A S. pyogenes
- D. All opportunistic bacterial species
Correct Answer: A
Rationale: The correct answer is A: E. coli 0157:H7. This strain of E. coli has acquired virulence factors that allow it to cause severe illness in humans, such as bloody diarrhea and kidney failure. The transformation of E. coli from a commensal to a pathogenic strain is well-documented. In contrast, choices B and C involve species that are inherently pathogenic and not commensal. Choice D is too broad and includes a wide range of bacterial species that do not necessarily originate from the normal flora. Therefore, E. coli 0157:H7 is the best example of a commensal bacterium that has turned pathogenic due to the acquisition of virulence factors.
Which characteristics are seen with acute transplant rejection (select all that apply)?
- A. Treatment is supportive
- B. Only occurs with transplanted kidneys
- C. Organ must be removed when it occurs
- D. The recipient’s T cytotoxic lymphocytes attack the foreign organ
Correct Answer: D
Rationale: Acute transplant rejection involves the recipient's T cytotoxic lymphocytes attacking the transplanted organ, requiring immunosuppressive therapy.