Which antibody class forms a secretory dimer protecting mucosal surfaces of the gastrointestinal and respiratory tracts?
Answer and explanation
Correct answer: B. Secretory Immunoglobulin A
IgA is produced as a dimer joined by a J chain and acquires a secretory component during transcytosis through epithelial cells, making it resistant to enzymatic proteolysis in mucosal secretions (saliva, tears, colostrum, GI fluids).
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