Question

A person with a deficit of IgA is likely to exhibit recurrent respiratory tract infections. Which of the following correctly explains the role of IgA in this scenario?

a. IgA functions as a B cell antigen receptor; without these receptors B cells are unable to protect us against pathogens on our body surfaces
b. IgA triggers release of histamine from cells in our mucous membranes, which is required for an inflammatory response to infection
c. IgA is the most abundant antibody in the plasma and plays a central role in protecting against bacterial infections on our body surfaces
d. IgA, found in the mucus lining of the respiratory tract, helps stop pathogens from attaching to epithelial surfaces and entering our body

Answer 1

Individuals with selective IgA deficiency suffer from recurrent respiratory infections due to the lack of secretory IgA in their mucus, which is essential for trapping pathogens and preventing them from invading the body via mucosal surfaces.

Step-by-step explanation:

The role of IgA in immune function is critical, especially in the mucosal immune system. IgA antibodies, particularly secretory IgA, are prevalent in the mucus secretions of the gastrointestinal and respiratory tracts, where they perform essential defense functions. Individuals with selective IgA deficiency display chronic respiratory tract infections because they lack secretory IgA, which serves to trap pathogens in mucus and prevent them from attaching to epithelial surfaces. Without functional IgA, these individuals are not able to efficiently prevent pathogens from entering the body and causing infection. Therefore, the correct explanation for why a person with a deficit of IgA would exhibit recurrent respiratory tract infections is that IgA, found in the mucus lining of the respiratory tract, helps stop pathogens from attaching to epithelial surfaces and entering our body.