Which of the following statements is NOT true

Correct Answer: B

Rationale: The correct answer is B: During T cell differentiation, the decision to become a TH1 or a TH2 cell CD4+ is not a random event. This is because T cell differentiation into TH1 or TH2 cells is guided by specific signals from the environment, such as cytokines present during activation. TH1 cells are induced by IL-12 and IFN-gamma, while TH2 cells are induced by IL-4. This process is not random but rather a result of specific signaling cues. A: During T cell development, the decision to become a CD4 or a CD8 positive cell is not a random event. It is determined by interactions with thymic stromal cells and the T cell receptor. C: TH2 CD4+ cells do secrete IL-4, so this statement is true. D: IL-10 is not a TH2 polarizing cytokine; rather, it is known to have regulatory functions in immune responses.

Correct Answer: D

Rationale: The correct answer is D: Able to induce only a humoral response. Live attenuated vaccines can induce both humoral and cellular immune responses, not just humoral. This is because they mimic natural infection, leading to a broader immune response. A: Usually effective at a single dose - This is true for live attenuated vaccines, as they often provide long-lasting immunity with just one dose. B: Expensive handling and storage - Live attenuated vaccines can be more cost-effective due to fewer doses needed, not expensive. C: Potential hazard due to reversion to a virulent form - This is a concern with live attenuated vaccines, as there is a risk of the weakened virus reverting to a virulent form.

Correct Answer: C

Rationale: The correct answer is C: Resolve DIC. Activated protein C is used in septic shock to address the coagulopathy associated with DIC, a common complication. Activated protein C inhibits clotting factors and promotes fibrinolysis, helping to restore normal coagulation function. This treatment does not directly dampen the cytokine storm (choice A), raise blood pressure (choice B), or boost the immune response (choice D) in septic shock patients. It specifically targets the coagulation abnormalities seen in DIC, making choice C the most appropriate answer.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: A

Rationale: The correct answer is A: Passage through cultured cells. Attenuated vaccines are produced by weakening the pathogen through serial passages in cultured cells, reducing virulence while maintaining immunogenicity. Formaldehyde treatment (B) disrupts the pathogen's structure and is used for inactivated vaccines. The use of viral vectors carrying pathogen subunits (C) is a method for creating subunit vaccines, not attenuated vaccines. Therefore, D is incorrect as not all treatments lead to attenuated vaccines.