Which of the following statements regarding human antibodies is/are accurate?
1. IgG constitutes the largest proportion of antibodies in human blood.
2. IgE plays a key role in allergic responses.
3. IgA is primarily located in bodily secretions such as saliva and breast milk.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 1, 2 and 3 all are correct.
Antibodies, or immunoglobulins, perform specialized immune functions. IgG is the most abundant (about 75–80%) and provides long-term immunity. IgE is found in trace amounts but is central to triggering allergic reactions and fighting parasitic infections. IgA exists primarily in "secretory" forms, protecting mucosal surfaces in the mouth, gut, and respiratory tract, and is passed to infants through breast milk. Together, these proteins form a critical defense against diverse pathogens.