Abstract A relevant proportion of allergy diagnosis is accom-plished by in vitro determination of specic im-munglobulin E (sIgE) to extracts from suspected allergens. Such extracts inevitably contain glycopro-teins, which may react with patients’IgE. In the case of plant and insect allergens, the relevant epitope
structure is an α-1,3-fucose on the Asn-linked sugar residue of so-called N-glycans. Due to their wide distribution, N-glycans carrying this epitope are
known as “cross-reactive carbohydrate determi-nant(s)” (CCD[s]). About 15 years of awareness al-low the conclusion that anti-CCD IgE does not cause noticeable clinical symptoms. In consequence, diagnostic results arising from CCD reactivity must be rated as false positives. With up to 30 % of CCD reactive patients, this can be regarded as a serious problem. Another cross-reactive carbohydrate determinant became notorious as a potential cause of anaphylac-tic reactions to a recombinant glycoprotein drug carrying α-1,3-galactose. is galactose-containing determinant (GalCD, galactose containing cross- reactive carbohydrate determinant) was supposed as a trigger for delayed allergic reactions to red meat
in several cases. us, α-1,3-galactose may have clin-ical relevance in certain cases – possibly as a result of tick bites. O–en, however, GalCDs probably cause
false-positive results with milk and meat extracts. No clear evidence for the role of other non-human carbohydrate structures such as N-glycolylneur-aminic acid as CCD has been presented so far. Remedies for sIgE based in vitro diagnosis come in the form of non-glycosylated recombinant aller-gen components or of specic CCD inhibitors. e high potential of recombinant allergens is optimally
realized in the context of component resolved dia-gnosis using allergen arrays with more than 100 components, whereas CCD inhibitors increase the specicity of conventional extract-based diagnosis. Reagents for the detection and inhibition of CCDs from plants and insects have been developed, whereas tools for GalCDs of milk and meat lag be-hind.