Which of the following immunoglobulins is first produced during acute infection

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2024

Microbiology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2024

Explanation

IgM is the first antibody class produced by B-cells during a primary immune response, making it a marker for acute infection.
Its large, pentameric structure provides ten antigen-binding sites, making it highly efficient at agglutinating (clumping) pathogens and activating the complement system early in an infection.
Clinically, detecting pathogen-specific IgM in a patient's serum is a standard method for diagnosing a recent or current infection.

Option A: IgG is the predominant antibody in the secondary immune response, not the first one produced during an acute (primary) infection. Its levels rise after IgM levels have started to decline.
Option B: IgE is primarily associated with type I hypersensitivity reactions (allergies) and the immune response to parasitic helminths (worms), not the initial response to most common acute infections.
Option D: IgD is found in very low levels in the blood and functions mainly as a surface receptor on B-lymphocytes, helping to activate them. It is not secreted in large quantities to fight an infection.

Clinical Relevance

Nursing practice connection: Knowing Primary immune response and immunoglobulin classes helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
In clinical diagnostics, serology tests that measure IgM and IgG levels are essential for staging an infection. High IgM indicates a recent or active infection, whereas high IgG with low IgM suggests a past infection or immunity from vaccination.
This principle is used to diagnose diseases like hepatitis, rubella, and COVID-19, guiding patient management and public health measures.
What if? If a newborn shows high levels of a specific IgM, it indicates an intrauterine infection (e.g., congenital rubella), as maternal IgM cannot cross the placenta. In contrast, the presence of IgG in a newborn reflects passive immunity transferred from the mother.

How to Approach the Question

This is a factual recall question testing your knowledge of immunology.
First, identify the keywords in the question: 'first produced' and 'acute infection'. These point to the primary immune response.
Next, recall the sequence of antibody production. The immune system mounts an initial, rapid response followed by a more sustained, memory response.
Associate IgM with the initial, acute phase. Its name can be remembered as 'Ig-Immediate' or 'Ig-Military' (first troops on the scene).
Associate IgG with the later, memory phase. Its name can be remembered as 'Ig-Gone' (for a past infection) or 'Ig-Guardian' (long-term protection).
Eliminate the other options based on their specific roles: IgE for allergies/parasites and IgD as a B-cell receptor.

Concept Tested & Keywords

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