Immune System Quizlet

Immune System Quizlet Related

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What is the outcome of clonal selection after a lymphocyte is activated?

  • A. Cytokine suppression
  • B. Formation of memory and effector cells
  • C. Antigen elimination without cellular proliferation
  • D. Destruction of the lymphocyte
Correct Answer: B

Rationale: The correct answer is B because clonal selection during lymphocyte activation leads to the formation of memory and effector cells. This process involves the proliferation and differentiation of the activated lymphocyte into these specialized cells, which play crucial roles in immune responses upon encountering the same antigen in the future. Cytokine suppression (choice A) is not the direct outcome of clonal selection but may be a regulatory mechanism during immune responses. Antigen elimination without cellular proliferation (choice C) is not accurate as clonal selection involves the expansion of specific lymphocyte clones. Destruction of the lymphocyte (choice D) is not the outcome of clonal selection, as activated lymphocytes undergo proliferation and differentiation rather than destruction.

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Which of the following causes memory cells to convert to plasma cells?

  • A. An organ transplant
  • B. Release of lymphokines
  • C. Re-exposure to a specific antigen
  • D. Initial exposure to an antigen
Correct Answer: C

Rationale: Memory cells convert to plasma cells upon re-exposure to a specific antigen which triggers a rapid and robust immune response.

Autoimmune diseases are associated with several susceptibility factors. Environmental factors associated with increased risk of autoimmune disease include:

  • A. Infections
  • B. Level of exposure to the sun
  • C. Imbalance of microbiota composition
  • D. All of the above
Correct Answer: D

Rationale: The correct answer is D, "All of the above." Autoimmune diseases have complex causes, involving genetic predisposition and environmental factors. Infections can trigger autoimmune responses, sunlight exposure can influence immune function, and an imbalance in microbiota composition can lead to dysregulated immune responses. Therefore, all three factors can contribute to an increased risk of autoimmune diseases. Choices A, B, and C individually are all associated with autoimmune diseases, making option D the correct choice.

AIRE is expressed in

  • A. Bone marrow
  • B. Thymic cortical region
  • C. Thymic medullary region
  • D. LN cortex
Correct Answer: C

Rationale: The correct answer is C: Thymic medullary region. AIRE (Autoimmune Regulator) is expressed in the thymic medullary region. This region is crucial for central tolerance by deleting self-reactive T cells to prevent autoimmune reactions. AIRE regulates the expression of tissue-specific antigens in medullary thymic epithelial cells, leading to negative selection of autoreactive T cells. Choices A, B, and D are incorrect as AIRE is not primarily expressed in bone marrow, thymic cortical region, or LN cortex.

What is the medical term for an abnormal decrease in platelets?

  • A. Leukopenia
  • B. Thrombocytopenia
  • C. Anemia
  • D. Hemolysis
Correct Answer: B

Rationale: The correct answer is B: Thrombocytopenia, which refers to an abnormal decrease in platelets. Platelets are crucial for blood clotting. Leukopenia (A) is a decrease in white blood cells, not platelets. Anemia (C) is a decrease in red blood cells, not platelets. Hemolysis (D) is the breakdown of red blood cells, not related to platelet count. Therefore, B is the correct answer as it specifically addresses a decrease in platelet count, leading to potential bleeding issues.

Prophylactic measures that are routinely used as early as possible in HIV infection to prevent opportunistic and debilitating secondary problems include administration of

  • A. isoniazid (INH) to prevent tuberculosis
  • B. trimethoprim/sulfamethoxazole (TMP/SMX) for toxoplasmosis
  • C. vaccines for pneumococcal pneumonia, influenza, and hepatitis A and B
  • D. varicella-zoster immune globulin (VZIG) to prevent chickenpox or shingles
Correct Answer: C

Rationale: Vaccination protects against preventable infections that can become severe in immunocompromised individuals.

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