While α-galactose as a part of glycoprotein glycans from vertebrates other than higher apes was known for a long time as being a prominent xeno-antigen, its implication in allergy only began to materialize when complications during treatment with a recombinant monoclonal antibody (Erbitux) were attributed to IgE directed against α-Gal containing N-glycans on this antibody. The incidencies of anaphylaxis due to Erbitux were confined to a certain area in the eastern United States, which raised speculations about the involvement of a particular type of tick endemic in this area. However, IgE antibodies against the α-Gal epitope should be taken into account in the diagnosis of milk and meat allergy. It is currently largely unexplored whether this type of CCD is generally also clinically irrelevant such as the plant/insect CCDs. The very localized case of Erbitux complications points at a possible if rare clinical significance of α-Gal.
Yet other potentially immunogenic carbohydrates with widespread occurrence such as N-Glycolylneuraminic acid, which does not occur in humans, or plant O-glycans (arabinogalactans and arabinans) may be mentioned but have so far not qualified as either IgE or as cross-reactive determinants.
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