The immunity transferred by maternal antibodies across the placenta is called?

NVS Staff Nurse - 2019

Microbiology

Easy

Appeared in: NVS Staff Nurse - 2019

Explanation

Passive immunity is defined by the transfer of pre-formed antibodies from one individual to another, providing immediate protection.
The question describes a classic example of naturally acquired passive immunity, where maternal IgG antibodies are transported across the placenta to the fetus.
This process does not involve the fetus's own immune system producing antibodies, which is the key feature distinguishing it from active immunity.

Option B: Active immunity involves the body producing its own antibodies after exposure to an antigen, either through infection or vaccination. The fetus is receiving antibodies, not producing them.
Option C: Herd immunity is a form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, thereby providing a measure of protection for individuals who are not immune. It is a population-level phenomenon, not an individual one.
Option D: Humoral immunity is a broad category of adaptive immunity that is mediated by antibodies. While the transfer of antibodies is part of humoral immunity, 'passive immunity' is the more specific term that describes how the immunity was acquired (i.e., passively received).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Types of immunity, specifically passive versus active immunity as background academic context rather than a clinical decision trigger.
The passive immunity a newborn receives from the mother typically lasts for the first few months of life, protecting them while their own immune system matures.
Premature infants are at higher risk for infections because they are born before the full transfer of maternal IgG is completed in the third trimester.
What if? If a mother has a specific autoimmune disease where her body produces harmful IgG antibodies (e.g., myasthenia gravis), these can also cross the placenta and cause a temporary, neonatal form of the disease in the infant.

How to Approach the Question

First, identify the keywords in the question: 'immunity', 'transferred', 'maternal antibodies', and 'placenta'.
The word 'transferred' is the most critical clue. It implies that the immunity is being given to, not created by, the recipient.
Recall the definitions of the main types of immunity. 'Passive' means received, while 'Active' means produced by one's own body.
Since the antibodies are being transferred from mother to fetus, this is a passive process.
Evaluate the other options. 'Active' is the opposite. 'Herd' is about populations. 'Humoral' is too general. Therefore, 'Passive immunity' is the most specific and correct answer.

Concept Tested & Keywords

Q-gm8b_uhy3xiZel341UOx

E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart A (pp 26-201 of 604) p. 95-97

E6 Microbiology Applied AnjuDhir 3e Part 2 p. 88-90

E6 Pharmacology Nursing Lilley 11e Part 3 p. 148-150