International Board of Certified Lactation Consultant (IBCLC) Practice Exam

Which immunoglobulin type primarily helps protect mucous membranes?

1. IgG

2. IgA

3. IgM

4. IgE

The correct answer is: IgA

Immunoglobulin A (IgA) is the antibody that primarily serves as a key player in protecting mucous membranes. It is found in high concentrations in mucosal areas such as the gastrointestinal tract, respiratory tract, and urogenital tract, as well as in secretions like saliva, tears, and breast milk. IgA works by neutralizing pathogens and preventing them from adhering to and penetrating mucosal epithelial cells, thus playing a crucial role in the body's first line of defense against infections. In breastfeeding, maternal IgA is particularly important as it can convey passive immunity to the infant, providing essential protection against infections during the early months of life as their own immune system is still developing. The other immunoglobulin types have different roles; for instance, IgG is the most abundant antibody in serum and provides long-term immunity, IgM is primarily involved in the initial response to infections, and IgE is associated with allergic reactions and protection against parasitic infections but does not play a significant role in mucosal immunity.