Involvement of cross-reactive carbohydrate determinants-specific IgE in pollen allergy testing

Abstract

BackgroundSpecific IgE antibodies against the low-molecular-weight carbohydrate antigen that does not bridge IgE molecules on mast cells are not associated with clinical symptoms. Cross reactivity can be determined in allergen-specific IgE detection assays when the carbohydrate structures between pollen allergens and plant derived food allergens are similar; in such cases, false positive results for grain or legume allergens can be reported for pollen allergic patients who are not sensitized to those allergens. This phenomenon arises owing to the presence of cross-reactive carbohydrate determinants (CCDs).ObjectiveThis study aimed to assess the impact of CCD interference on the results for pollen allergen-specific IgE antibodies in the general adult population and to perform CCD inhibition tests evaluating the involvement of CCD on samples positive to pollen allergens.MethodsSerum samples from 322 subjects were tested for IgE antibodies to pollens and CCD. The research subjects were given questionnaires about pollen allergic symptoms to help assess the presence of allergies. Allergen IgE antibodies for Japanese cedar, Japanese cypress, orchard grass, ragweed, MUXF, bromelain, horseradish peroxidase (HRP), and ascorbate oxidase (ASOD) were analyzed.ResultsIt was observed that among individuals who tested positive to any of the pollen allergens, the positive ratio of CCD-specific IgE antibody was the highest for HRP (13.5%–50.0%). The results from the inhibition tests revealed that CCD was marginally present. Although IgE antibodies for cedar pollen did not react with CCD, IgE antibodies for Japanese cypress, orchard grass, and ragweed might be detected by the presence of CCD.ConclusionThe results of the inhibition tests revealed the obvious presence of CCD suggesting its involvement. Considering these findings, careful evaluation of patient IgE results should be performed for Japanese cypress, orchard grass, and ragweed.

Agreement of serum allergen test results with unblocked and blocked IgE against cross‐reactive carbohydrate determinants (CCD) and intradermal test results in atopic dogs

“…With grass and weed allergens, the inhibition of anti‐CCD IgE led to a marked decrease of polysensitization. As grasses and weeds share partially identical carbohydrate structural units of their glycoproteins (which are not present in mammals), anti‐CCD IgE can be produced against those antigens . In human medicine, anti‐CCD IgE antibodies were assumed to not contribute to clinical signs of hypersensitivity diseases .…”

Alpha-Gal and Cross-Reactive Carbohydrate Determinants in the N-Glycans of Salivary Glands in the Lone Star Tick, Amblyomma americanum

“…In addition, a trace amount of N-glycan structures carrying the terminal N-glycolylneuraminic acid, another CCD [31], was also detected in the SGs of partially fed ticks (Figure 4). Several different CCDs are shown to interact with specific IgE (sIgE), which can mediate a hypersensitive immune response leading to allergies to certain plants and insect venoms [48]. However, clinical importance of the CCD as the causal factors of allergy is yet unclear, while correlation between sIgE activities against the specific CCD and the clinical symptoms has been shown [31,49].…”

Assessment of the potential allergenicity of genetically-engineered food crops

“…Up to 30% of allergic patients generate specific anti-glycan IgE (Altmann 2016). Despite antibody-binding glycol-proteins being common in foods, insect venoms, and pollen, cross-reactive carbohydrate determinants do not appear to cause clinical symptoms in patients and should be rated as false positives (Mari 2002;Ebo et al 2004;Altmann 2007Altmann , 2016Yokoi et al 2017). Furthermore, there are many glycosylated proteins that are not allergenic.…”