Question

Which antibody can cross the placenta?

• A. IgE
• B. IgA
• C. IgG
• D. IgM

Answer 1

The correct option is C

IgG

The correct option is C.

Explanation of correct option:

1. IgG is the only antibody that crosses the placenta.
2. Provides protection to newborns via passive immunization.
3. It neutralizes bacterial toxins.
4. It facilitates the process of phagocytosis.
5. Provides immunity to the developing fetus.

Explanation of incorrect options:

Option A

1. Allergic reactions are associated with IgE.
2. It is present in the linings of the respiratory and intestinal tracts.
3. IgE plays a vital role in responses to allergens.

Option B

1. IgA acts as the first line of defense.
2. IgA has a critical role in immune defense at mucosal surfaces.
3. It activates complement pathways.

Option D

1. IgD participates in B cell activation and differentiation.
2. It involves the production of antibodies by B cells.
3. IgD play important role in immune regulation and tolerance.

Final answer: IgG is an antibody that can cross the placenta.