• cross-reactive carbohydrate determinants;
  • occupational allergy

Cross-reactive carbohydrate determinants (CCDs) are carbohydrate structures of plant and animal glycoproteins. For reasons of their wide distribution in plants and invertebrates, CCDs are implicated in a broad spectrum of IgE cross-reactiveness between pollen, plant foods, insect venoms. The role of CCDs in diagnostics of occupational allergy (OA) remains unclarified and its clinical relevance is still questioned. Specific IgE (sIgE) to CCDs can be highly crossreactive and frequently occur in patients with polyvalent not occupational sensitization. It is pointed out that the discrepancies between negative skin test responses and positive sIgE detection can be associated with the presence of CCD-sIgE (1).

The aim of the study was to evaluate the prevalence of CCDs in the subjects with suspected OA. When designing the study, we assumed that patients with suspected OA who had both sIgE to occupational allergens and sIgE to CCD present in serum were most likely not to have OA.

The study group included 81 patients: bakers, farmers, heath care workers and carpenters (56 males and 25 females) aged 20–59 years (mean age 38.5 ± 11.6 years) who were hospitalized in the Department of Occupational Diseases with suspicion of OA. They underwent physical examination, skin prick tests (SPT) to common and occupational allergens, total IgE level, sIgE determinations (k82, k87, fx20, ex4 ImmunoCap, Phadia AB, Sweden) and specific inhalation test. Moreover, for investigating the cross-reactivity between a glycan and other glycoproteins, MUXF3 CCDs and maltose binding protein (MBP) (Ro214, Ro213 ImmunoCap) were performed in all subjects.

In 48 of 81 enrolled patients (59.8%) occupational asthma and/or occupational rhinitis was recognized. Specific IgE to MUXF3 CCDs were found in eight subjects (9.8%) (Table 1). In most cases, level of sIgE to CCDs remained in class 1, only in one serum, the level reached class 2. Positive SPT to common allergens were found more frequently in subjects CCDs positive (six persons), while hypersensitivity to occupational agents was found rarely in that group (three subjects). In all subjects with CCDs, the sIgE to occupational allergen were detected. However, isolated allergy to occupational allergens was not found among patients with asIgE to CCDs. Surprisingly, OA was recognized in six cases among CCD’s positive patients.

Table 1.   The questionnaire data and results of SPT and sIgE among CCD-positive individuals [n = 8] (+ positive result, − negative result)
 Patient number
  1. SPT, skin prick tests; sIgE, specific IgE; CCDs, cross-reactive carbohydrate determinants.

 Farmer     ++ 
 Nurse       +
Positive SPT with at least one common allergen++++++
Positive SPT with at least one occupational allergen+++
Total IgE level (IU/ml) 813.78252.64278.01334.69141.6340.481000
Positive sIgE to occupational allergen++++++++
 sIgE to alpha-amylase (k87) concentration (class)1.6 (2)   
 sIgE to flours (wheat, rye, rice, barley) (Fx20) +++++ + 
 sIgE to latex (k82) concentration (class)       22 (4)
 sIgE to cow fur (ex4)      ++ 
Occupational allergy disease++++++
CCDs result-concentration (class)2.77 (2)0.58 (1)0.7 (1)0.65 (1)0.64 (1)0.4 (1)0.58 (1)0.38 (1)

Several reports demonstrated the lack of clinical relevance of plant glycan-specific IgE antibodies (2–4). On the other hand, there are preliminary data favouring clinical role of CCDs mainly in patients allergic to food allergens (5). Generally, the prevalence of anti-CCD IgE has been estimated to be 10–15% in patients with grass pollen allergy and increases up to 60% in patients with concomitant sensitisation to pollen from trees, grasses and weeds (1, 6). About 5% of nonallergic individuals have CCD-sIgE antibodies as well as 10% of nonpollen allergic subjects (1). There are little data regarding the prevalence of CCDs among patients with OA. Raulf-Heimsoth et al. (7) reported that 12 from 104 heath care workers sera contained sIgE that reacted with the carbohydrate determinants. Additionally, according to previous results, in our study, MBP was not found in tested patients’ serum.

As anti-CCD IgE antibodies mainly appear incapable of provoking clinical symptoms despite their frequent presence in serum, unexpectedly we found OA (confirmed by specific bronchial challenge) among six from eight CCDs positive patients. In these cases, the polysensitization (to both common and occupational allergens) must be explained by multiple independent sensitization more likely than cross-reactivity between proteins or glycoproteins. It has been pointed out that anti-CCD IgE may lead to false-positive results in in vitro testing (8). In our study, patients with clinically confirmed OA displayed the presence of sIgE to occupational allergens. Therefore, we consider these results to be clinically significant in spite of coexistence of CCDs in serum, when crossreactivity with common allergens might be suspected.

In conclusion, specific IgE to CCDs can be found in about 10% subjects with suspected OA. The preliminary results indicate that detection of CCDs in serum is not helpful in differentiation diagnostics of occupational and non OA.


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  2. References
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