Nokea
Which of the following is NOT true with respect to T cell development?
- A. It establishes MHC restriction of the T cell repertoire
- B. It takes place in the thymus
- C. Thymic dendritic cells are involved
- D. It only occurs after the naïve T cell has been activated by antigen
Correct Answer: D
Rationale: The correct answer is D because T cell development starts in the thymus while the naïve T cell activation by antigen occurs outside of the thymus. T cell development involves positive and negative selection, establishing MHC restriction, and interaction with thymic dendritic cells for maturation. Naïve T cells are activated by antigens in the periphery, not during T cell development in the thymus. Therefore, D is the correct answer as it does not align with the process of T cell development.
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Which of the following is an example of a live attenuated bacterial vaccine?
- A. Cholera
- B. Typhoid
- C. Anthrax
- D. Plague
Correct Answer: B
Rationale: The correct answer is B: Typhoid. Live attenuated vaccines contain weakened forms of the pathogen that can replicate in the host to stimulate a strong immune response without causing disease. Typhoid vaccine is an example of a live attenuated bacterial vaccine because it contains weakened Salmonella typhi bacteria. Cholera (A), Anthrax (C), and Plague (D) vaccines are not live attenuated bacterial vaccines; they are either killed/inactivated or subunit vaccines. Live attenuated vaccines provide longer-lasting immunity compared to other vaccine types.
The patient is experiencing fibrosis and glomerulopathy a year after a kidney transplant. Which type of rejection is occurring?
- A. Acute
- B. Chronic
- C. Delayed
- D. Hyperacute
Correct Answer: B
Rationale: Chronic rejection occurs over time and involves fibrosis and structural changes in the transplanted organ.
What is a hallmark of Type IV hypersensitivity?
- A. It is immediate and IgE-mediated
- B. It is delayed and T cell-mediated
- C. It involves immune complexes
- D. It stimulates mast cells to release histamine
Correct Answer: B
Rationale: The correct answer is B because Type IV hypersensitivity reactions are delayed and T cell-mediated. Upon exposure to an antigen, sensitized T cells, specifically CD4+ T cells, release cytokines that recruit and activate macrophages and other effector cells, leading to tissue damage. Choice A is incorrect because Type I hypersensitivity reactions are immediate and IgE-mediated. Choice C is incorrect because immune complex-mediated hypersensitivity reactions are typically associated with Type III hypersensitivity. Choice D is incorrect because histamine release by mast cells is characteristic of Type I hypersensitivity reactions, not Type IV.
The physician plans to prescribe trastuzumab (Herceptin) for the patient with breast cancer. What testing will the physician order before prescribing this medication?
- A. HER2 protein levels
- B. BRCA2 gene mutation
- C. BRCA1 gene mutation
- D. Stage II cancer identification
Correct Answer: A
Rationale: Trastuzumab targets HER2-positive breast cancers, so HER2 protein level testing is essential to determine eligibility.
One of the most significant factors in determining when to start antiretroviral therapy in a patient with HIV infection is:
- A. Whether the patient has high levels of HIV antibodies
- B. Confirmation that the patient has contracted HIV infection
- C. The patient’s readiness to commit to a complex, lifelong, uncomfortable drug regimen
- D. Whether the patient has a support system to help manage the costs and side effects of the drugs
Correct Answer: C
Rationale: Patient adherence is critical for successful antiretroviral therapy. Ensuring the patient is prepared to follow the regimen long-term improves outcomes.