Alpha-gal allergy

Described in 2015, revolutionary in that allergy is to an oligosaccharide (ie a sugar, not a protein), specifically galactose-alpha-1,3-galactose.

Accounts for anaphylaxis to cetuximab, a cancer drug, but even more bizarrely, allergy to red meat (beef and pork). The latter appears to follow sensitization through a tick bite, so is really only an issue in endemic areas eg parts of United States and Europe, Australia.

Anaphylaxis to red meat can be immediate or delayed, with or without exercise induction!

In a small series of beef allergic patients reported in 2003 (strong family history), skin prick and labial contact tests only positive in minority.  All positive on IgE.  In another series, most beef allergic were also gelatine allergic.  Interestingly, a proportion of “idiopathic” anaphylaxis turned out SPT positive for gelatine. 

Bovine specific albumin is another possible allergen for beef allergy.

In Asia allergy described to galacto-oligosaccharides in milk formula, also a carbohydrate!

Thought to be T cell indepedent!

IgE test available.

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