Q37. Match the items in Group 1 with those in Group 2
| Group 1 | Group 2 |
|---|---|
| P. Isotype switching Q. Clonal anergy R. Class II MHC S. Self tolerance |
1. VH domain 2. Non-responsive to self antigen 3. Non-responsive TH cells 4. β2-microglobulin |
Isotype switching involves B cells changing antibody classes while retaining antigen specificity, and this matching question tests key immunology concepts for exams like GATE Life Sciences. The correct answer is option (C).
Group 1-Group 2 Matches
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P. Isotype switching → 1. VH domain: Matches because isotype switching keeps the variable heavy (VH) domain unchanged, only altering the constant region for different effector functions.
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Q. Clonal anergy → 3. Non-responsive TH cells: Matches as clonal anergy renders T helper (TH) cells unresponsive to antigens without co-stimulation.
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R. Class II MHC → 4. β2-microglobulin: Matches because Class II MHC lacks β2-microglobulin (which is specific to Class I MHC) and presents to CD4+ TH cells.
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S. Self tolerance → 2. Non-responsive to self antigen: Matches since self tolerance mechanisms like anergy make lymphocytes non-responsive to self antigens.
Option Analysis
Option (A): P-1, Q-4, R-3, S-2
Incorrect. Q (clonal anergy) wrongly pairs with 4 (β2-microglobulin, unrelated to T cell anergy); R (Class II MHC) mismatches 3 (TH cell response, but β2-microglobulin defines Class I).
Option (B): P-2, Q-4, R-1, S-3
Incorrect. P (isotype switching) mismatches 2 (self antigen response); Q pairs wrongly with 4; R (Class II) mismatches VH domain.
Option (C): P-1, Q-3, R-4, S-2
Correct, as detailed in matches above.
Option (D): P-2, Q-1, R-3, S-4
Incorrect. P mismatches 2; Q (anergy) mismatches VH; S mismatches β2-microglobulin.
Isotype switching clonal anergy questions are high-yield for GATE Life Sciences, testing immunology matching of Group 1 (P-Q-R-S) with Group 2 (VH domain, non-responsive states, β2-microglobulin).
Core Concepts
Isotype switching lets B cells swap constant regions (IgM to IgG) via CSR, preserving VH domain specificity. Clonal anergy induces non-responsive TH cells when self-antigens lack co-stimulation. Class II MHC (no β2-microglobulin) activates CD4+ cells; self tolerance ensures non-responsiveness to self antigens.
Exam Matching Strategy
Use process of elimination: Link isotype switching only to VH (unchanged); anergy to TH cells; Class II to absent β2-microglobulin; tolerance to self antigen silence.
| Group 1 | Correct Group 2 | Why It Matches |
|---|---|---|
| P. Isotype switching | 1. VH domain | Variable region retained |
| Q. Clonal anergy | 3. Non-responsive TH cells | T cell inactivation |
| R. Class II MHC | 4. β2-microglobulin | Absent in Class II |
| S. Self tolerance | 2. Non-responsive to self antigen | Core mechanism |
This PYQ pattern repeats in CSIR NET—focus on distinctions for scoring.
