Immune impairment affects which protective mechanism of the GI tract?

Immune impairment affects which protective mechanism of the GI tract?

• A. Gastric acid
• B. Mucosal IgA
• C. Mucus
• D. Tight junctions

Answer: (B)

Secretory IgA at the mucosal surface is the key immune defense in the GI tract. It’s produced by plasma cells in the lamina propria and transported into the lumen as secretory IgA, where it neutralizes pathogens and toxins, and prevents bacteria and viruses from attaching to and invading the mucosal epithelium. This immune exclusion happens with minimal inflammation, helping keep the gut environment stable while keeping pathogens in check. If immune function is impaired, the mucosal IgA response is reduced, compromising this frontline defense and increasing susceptibility to mucosal infections. The other barriers—gastric acid (a chemical barrier), mucus (a physical barrier of mucins), and tight junctions (cellular connections that maintain barrier integrity)—are important but are not immune components themselves, so they’re less directly affected by immune impairment.

Secretory IgA at the mucosal surface is the key immune defense in the GI tract. It’s produced by plasma cells in the lamina propria and transported into the lumen as secretory IgA, where it neutralizes pathogens and toxins, and prevents bacteria and viruses from attaching to and invading the mucosal epithelium. This immune exclusion happens with minimal inflammation, helping keep the gut environment stable while keeping pathogens in check.

If immune function is impaired, the mucosal IgA response is reduced, compromising this frontline defense and increasing susceptibility to mucosal infections. The other barriers—gastric acid (a chemical barrier), mucus (a physical barrier of mucins), and tight junctions (cellular connections that maintain barrier integrity)—are important but are not immune components themselves, so they’re less directly affected by immune impairment.