The immunological protection conferred by breast milk is largely associated with______________?
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Answer: D. IgA antibodies
Explanation
Secretory IgA is the predominant immunoglobulin isotype found in high concentrations in human breast milk. It resists enzymatic degradation in the infant gastrointestinal tract, remaining stable in acidic conditions. This antibody provides passive immunological protection by binding pathogens and preventing their attachment to mucosal surfaces. Breast milk contains numerous bioactive components, including antibodies, leukocytes, cytokines, and antimicrobial enzymes. Maternal B cells in mammary glands produce secretory IgA directed against pathogens the mother has encountered. Passive transfer of immunity helps protect newborns while their own adaptive immune systems continue developing.
Option A names IgM, which is a primary serum antibody but is not the major protective isotype secreted in milk. Option B lists lysozyme, an antimicrobial enzyme present in milk that aids defense but is not an antibody. Option C names mast cells, which are tissue-dwelling immune cells involved in allergic reactions, not milk components.
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