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Question #46538
The Question
A patient suffering from a severe helminthic infection exhibits intense allergic manifestations. To confirm the infection, a technician performs an indirect ELISA using the helminth antigen and an enzyme-linked anti-human IgG secondary antibody. Despite active infection and high sensitization, the ELISA yields a false-negative result. Which of the following best explains this discrepancy?
Options
- A.
The predominant antibody produced is IgE, which lacks structural homology in its Fc region with IgG, preventing the secondary antibody from binding.
- B.
The heavy chains of the patient's antibodies are of the mu type, which competitively inhibit the binding of the anti-human IgG.
- C.
IgE antibodies are highly unstable in vitro and rapidly degrade before the addition of the chromogenic substrate.
- D.
The massive release of histamine and serotonin from mast cells denatures the parasitic antigens coated on the ELISA plate.
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
IgE|ELISA|Mast Cells|Allergy Mechanism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'ELISA detects antibodies' (NCERT Biotech) but fail to integrate antibody structure (NCERT Health).
They must realize that secondary antibodies in ELISA are isotype-specific (e.g., anti-IgG targets the gamma heavy chain) and will not cross-react with IgE (epsilon heavy chain) produced during allergic/helminthic responses.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Human Health and Disease - Class 12 |
| Concept | ELISA Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |