Analysis of human milk from lactating mothers shows that it contains IgA antibodies against infections that were recent (1 year). These antibodies are directed against a host of organisms, including viruses, such as enteroviruses, herpes simplex viruses, respiratory syncytial virus, rubella, reovirus, and rotavirus. In addition, IgA antibodies against many bacteria are found in human milk, including those reactive to E. coli, Shigella, Salmonella, Campylobacter, Vibrio cholerae, H. influenzae, S. pneumoniae, Clostridium difficile, C. botulinum, and Klebsiella pneumoniae. IgA antibodies to the parasite Giardia and the fungus, Candida albicans, are also seen in human milk. Since most of these infections were localized in the gastrointestinal tract of the mother, these IgA antibodies ended up in breast milk by:

Question

Analysis of human milk from lactating mothers shows that it contains IgA antibodies against infections that were recent (<3 weeks earlier) and those from the distant past (>1 year). These antibodies are directed against a host of organisms, including viruses, such as enteroviruses, herpes simplex viruses, respiratory syncytial virus, rubella, reovirus, and rotavirus. In addition, IgA antibodies against many bacteria are found in human milk, including those reactive to E. coli, Shigella, Salmonella, Campylobacter, Vibrio cholerae, H. influenzae, S. pneumoniae, Clostridium difficile, C. botulinum, and Klebsiella pneumoniae. IgA antibodies to the parasite Giardia and the fungus, Candida albicans, are also seen in human milk. Since most of these infections were localized in the gastrointestinal tract of the mother, these IgA antibodies ended up in breast milk by:

Quizplus · Accepted Answer

The presence of IgA antibodies against gastrointestinal infections in human milk suggests that gut-primed activated B cells are trafficking from the mother's circulation into the lactating milk gland. These B cells are able to secrete IgA antibodies specific to the infecting pathogens. Option A is incorrect because it implies that the antibodies are being transported from the lymph fluid in the breast tissue, which is not the case. Option B is incorrect because germinal center B cells are not known to traffic to the breast epithelium. Option D is incorrect because activated B cells do not traffic to all secondary lymphoid tissues in the mother. Option E is incorrect because activated B cells primed in the spleen are not known to switch to IgA secretion after entering the mother's lactating milk gland.

Analysis of Human Milk from Lactating Mothers Shows That It