Galactose-''alpha''-1,3-galactose, commonly known as alpha gal and the Galili antigen, is a
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...
found in most
mammalian cell membranes. It is not found in
catarrhine
The parvorder Catarrhini , catarrhine monkeys, Old World anthropoids, or Old World monkeys, consisting of the Cercopithecoidea and apes (Hominoidea). In 1812, Geoffroy grouped those two groups together and established the name Catarrhini, "Old ...
s, including humans, who have lost the GGTA1 gene. Their immune systems recognize it as a foreign body and produce xenoreactive
immunoglobulin M antibodies, leading to organ rejection after transplantation.
Anti-alpha gal
immunoglobulin G antibodies are some of the most common in humans. Regular stimulation from gut flora, typically initiated within the first six months of life, leads to an exceptionally high titre of around 1% of all circulating IgG.
Alpha gal has also been suggested to play a role in an
IgE
Immunoglobulin E (IgE) is a type of antibody (or immunoglobulin (Ig) " isotype") that has been found only in mammals. IgE is synthesised by plasma cells. Monomers of IgE consist of two heavy chains (ε chain) and two light chains, with the ε c ...
-specific allergic response to some meats.
While this allergic response is quite well documented, there is significant discrepancy between laboratory tests and clinical findings, indicating that much research must still be done on the alpha gal mechanism of action and related tests. Recent studies are showing increasing evidence that this allergy may be induced by the bite of the
lone star tick
''Amblyomma americanum'', also known as the lone star tick, the northeastern water tick, or the turkey tick, or the "Cricker Tick", is a type of tick indigenous to much of the eastern United States and Mexico, that bites painlessly and commonly ...
(''Amblyomma americanum'') in North America and the
castor bean tick
''Ixodes ricinus'', the castor bean tick, is a chiefly European species of hard-bodied tick. It may reach a length of when engorged with a blood meal, and can transmit both bacterial and viral pathogens such as the causative agents of Lyme disea ...
(''Ixodes ricinus'') in Sweden.
A bacterial
alpha-galactosidase
α-Galactosidase ( EC 3.2.1.22, α-GAL, α-GAL A; systematic name α-D-galactoside galactohydrolase) is a glycoside hydrolase enzyme that catalyses the following reaction:
: Hydrolysis of terminal, non-reducing α-D-galactose residues in α-D ...
that efficiently removes linear alpha-gal ends from molecules has been identified. It could be useful for
xenotransplantation
Xenotransplantation (''xenos-'' from the Greek meaning "foreign" or strange), or heterologous transplant, is the transplantation of living cells, tissues or organs from one species to another. Such cells, tissues or organs are called xenograft ...
in the future. Human reaction to alpha-gal has beneficial uses as a
vaccine adjuvant
In immunology, an adjuvant is a substance that increases or modulates the immune response to a vaccine. The word "adjuvant" comes from the Latin word ''adiuvare'', meaning to help or aid. "An immunologic adjuvant is defined as any substance that ...
and for enhancing wound healing.
See also
*
Alpha-gal allergy
Alpha-gal allergy — or mammalian meat allergy (MMA) — is a type of meat allergy characterized by a delayed onset of symptoms (3–8 hours) after ingesting mammalian meat and resulting from past exposure to tick bites. It was first reported in ...
*
Galactose
Galactose (, '' galacto-'' + ''-ose'', "milk sugar"), sometimes abbreviated Gal, is a monosaccharide sugar that is about as sweet as glucose, and about 65% as sweet as sucrose. It is an aldohexose and a C-4 epimer of glucose. A galactose molecu ...
References
External links
GGTA1 Pseudogene
{{Carbohydrates
Allergology
Food allergies
Disaccharides