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Question #45218
The Question
Cyclosporin A, a bioactive molecule extracted from the fungus Trichoderma polysporum, is extensively used as an immunosuppressive agent to prevent allograft rejection. It exerts its effect by interfering with the intracellular signaling cascade of lymphocytes. Which of the following statements regarding its mechanism of action is INCORRECT?
Options
- A.
It primarily suppresses cell-mediated immunity, which is the principal immune response responsible for the rejection of transplanted organs.
- B.
It binds to cytoplasmic cyclophilins, forming a specific structural complex that targets and inhibits the phosphatase activity of calcineurin.
- C.
It prevents the dephosphorylation of the transcription factor NFAT, thereby blocking its nuclear translocation and halting Interleukin-2 (IL-2) transcription.
- D.
It suppresses the humoral immune response by directly binding to and altering the secondary structure of circulating immunoglobulins, preventing graft opsonization.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Cyclosporin_A_Immunomodulation|T_Cell_Receptors|Hydrogen_Bonding
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The distinction between Cell-Mediated Immunity (T-cells) and Humoral Immunity (B-cells/Antibodies) in the context of graft rejection.
A common misconception is that immunosuppressants broadly destroy circulating antibodies.
The question tests the student's ability to link the NCERT fact (Cyclosporin A prevents graft rejection via CMI suppression) with the advanced molecular mechanism (intracellular inhibition of the calcineurin-NFAT pathway via conformational protein complexes), effectively trapping those who confuse the branches of adaptive immunity or the cellular location of the drug's action.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Secondary Protein Structure Stabilizers |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |