milk immunity
{{Short description|Protection provided to immune system via milk}}
Milk immunity is the protection provided to immune system of an infant via the biologically active components in milk, typically provided by the infant's mother.
Mammalian milk
All mammalian milk contains water, sugar, fat, vitamins, and protein with the variation within and between species and individuals differing mainly in the amount of these components.{{Cite book |last1=Power |first1=Michael L. |title=The Biology of Lactation Milk |last2=Schulkin |first2=Jay |publisher=Johns Hopkins University Press |year=2016 |isbn=978-1-4214-2043-1 |location=Baltimore, Maryland |pages=4}} Other than the variation in quantity of these components, not a lot is known about bio-active or immune-modulating factors in many mammalian species. However, in comparison to other mammalian milk, human milk has the most oligosaccharide diversity.{{Cite book |last1=Martin |first1=M.A. |title=Building Babies |last2=Sela |first2=D.A. |year=2013 |publisher=Springer |location=New York |isbn=9781461440598 |editor-last=Clancy |editor-first=KB |pages=233–256 |chapter=Infant Gut Microbiota: Developmental Influences and Health Outcomes |doi=10.1007/978-1-4614-4060-4_11 |editor-last2=Hinde |editor-first2=K |editor-last3=Rutherford |editor-first3=JN}}
= Bovine milk =
Ruminant mothers do not transfer immunity to their infants during pregnancy, which makes milk the first introduction to maternal immunity calves receive.{{Cite journal |vauthors=Stelwagen K, Carpenter E, Haigh B, Hodgkinson A, Wheeler TT |date=April 2009 |title=Immune components of bovine colostrum and milk |journal=Journal of Animal Science |volume=87 |issue=13 Suppl |pages=3–9 |doi=10.2527/jas.2008-1377 |pmid=18952725 |s2cid=43829526}} Bovine milk contains both immunoglobulins A and G, but in contrast to human milk where IgA is the most abundant, IgG is more abundant.{{Cite journal |vauthors=Cakebread JA, Humphrey R, Hodgkinson AJ |date=August 2015 |title=Immunoglobulin A in Bovine Milk: A Potential Functional Food? |journal=Journal of Agricultural and Food Chemistry |volume=63 |issue=33 |pages=7311–6 |doi=10.1021/acs.jafc.5b01836 |pmid=26165692|url=https://figshare.com/articles/journal_contribution/22745003 }} Secretory Component, IgM, both anti-inflammatory and inflammatory cytokines, and other proteins with antimicrobial functions are also present in bovine milk.
= Human milk =
{{excerpt|Human milk immunity}}
Avian crop milk
Crop milk is a secretion from the crop of a bird that is regurgitated to feed their offspring.{{Cite journal |last1=Eraud |first1=Cyril |last2=Dorie |first2=Adrien |last3=Jacquet |first3=Anne |last4=Faivre |first4=Bruno |name-list-style=vanc |date=2008 |title=The crop milk: a potential new route for carotenoid-mediated parental effects |url=https://hal.archives-ouvertes.fr/hal-00294461/file/Eraud2008.pdf |journal=Journal of Avian Biology |volume=39 |issue=2 |pages=247–251 |doi=10.1111/j.0908-8857.2008.04053.x |issn=1600-048X |access-date=2022-06-14 |archive-date=2022-05-16 |archive-url=https://web.archive.org/web/20220516125840/https://hal.archives-ouvertes.fr/hal-00294461/file/Eraud2008.pdf |url-status=live }} Birds that produce this secretion include pigeons, flamingos, emperor penguins, and doves.{{Cite book |last1=Power |first1=Michael L. |title=The Biology of Lactation Milk |last2=Schulkin |first2=Jay |publisher=Johns Hopkins University Press |year=2016 |isbn=978-1-4214-2042-4 |location=Baltimore, Maryland |pages=26–27 |chapter=Feeding Offspring}} Pigeon milk contains some immune-modulating factors such as microbes and IgA, as well as other components with similar biological activities to mammalian milk including pigeon growth factor, and transferrin.{{Cite journal |vauthors=Gillespie MJ, Stanley D, Chen H, Donald JA, Nicholas KR, Moore RJ, Crowley TM |date=2012-10-26 |title=Functional similarities between pigeon 'milk' and mammalian milk: induction of immune gene expression and modification of the microbiota |journal=PLOS ONE |volume=7 |issue=10 |pages=e48363 |bibcode=2012PLoSO...748363G |doi=10.1371/journal.pone.0048363 |pmc=3482181 |pmid=23110233 |doi-access=free}}