Allergenic molecules
The World Health Organization (WHO) and International Union of Immunological Societies’ (IUIS) Allergen Nomenclature Subcommittee have registered four allergenic components, i.e., Cup s 1, Cup s 2, Cup s 3 and Cup s 7 for Italian cypress pollen (9).
Allergen |
Biochemical Name |
Molecular Weight (kDa) |
Allergenicity |
---|
Cup s 1 |
Pectate lyase |
43 |
- Major allergen
- A study conducted on 187 patients (2-14 years) with allergic rhino-conjunctivitis and/or asthma, 20.9% (39 out of 187) of patients showed specific-IgE (sIgE) reactivity towards Cup s 1 (22).
- Another study showed that, out of 30 cypress-pollen sensitized patients, 22 (73.3%) showed positive IgE-response towards Cup s 1 (23).
- High sequence similarity was noted between Cup s 1 and other cypress pollen allergens (Cry j 1, Cha o 1, Jun o 1, Jun v 1, Jun a 1, Cup a 1) (1).
|
Cup s 2 |
Polygalacturonase |
43 |
- In a study conducted among 30 cypress-pollen allergic patients, 21 (70%) were found sensitized towards Cup s 2 (23).
|
Cup s 3 |
Thaumatin-like protein |
34 |
- Major allergen
- In a study conducted on sera of 23 Italian cypress–allergic patients, IgE reactivity towards Cup s 3 was observed in 69.6% (16 of 23) of the patients (10).
- ~95% sequence similarity was observed between Cup s 3 and Jun a 3 (24)
|
Cup s 7 |
Gibberellin-regulated protein (GRP) |
9.5 |
- Five individuals sensitized to Pru p 7, Cry j 1 and Cup a 1, showed IgE-reactivity towards Cup s 7 allergen (25).
|
Allergen |
Biochemical Name |
Molecular Weight (kDa) |
Allergenicity |
---|
Biomarkers of severity
Cup s 1 is considered as a major allergen of Italian cypress pollen (C. sempervirens) with a study displaying specific immunoglobulin (Ig)E reactivity of 20.9% towards Cup s 1 (22). Where another study involving 30 cypress-pollen sensitised patients, 73.3% (n=22) showed positive IgE-response towards Cup s 1 allergen (23).
Cup s 3, another major allergen has been identified in Italian cypress pollen. This allergen was recognized on the basis of cross-reactivity and sequence homology with other cypress pollen allergens, despite exhibiting low protein expressions. Variations with respect to content of Cup s 3 allergen in pollens from various regions should be taken into consideration, while preparing extracts for diagnostic purposes (24).
Of interest, Cup a 1 from Cupressus Arizonica pollen has been identified as a genuine marker allergen for sensitization to cypress pollen (25).
Cross-reactivity
Italian cypress pollen has shown to cross-react and share high sequence homology with closely-related species, such as Arizona cypress, mountain juniper and Japanese cypress, belonging to the same family Cupressaceae and Japanese cedar which belongs to the same class Pinopsida as Italian Cypress (26).
High degree of sequence similarity i.e. 95.1% has been reported between Cup s 1 (Cupressus sempervirens) and Cup a 1 (Cupressus Arizonica) (27). Furthermore, Cup a 1 has shown to exhibit high sequence homology of 91% with Jun a 1 (Juniperus ashei), 75% with Cry j 1 (Cryptomeria japonica) and 81% with Cha o 1 (Chamaecyparis obtuse) (26, 28). These major allergens from the same family and class, are highly cross-reactive, as they share between 70% to 95% of sequence similarity (26).
Another major allergen from C. sempervirens species, Cup s 3 has revealed to have 95% sequence homology and strong cross-reactivity with Jun a 3 (J. ashei) (24).
Limited cross-reactivity was displayed between Italian cypress pollen, scrub cypress pine (Callitris verrucosa) and African fern pine (Podocarpus gracilior) (29).
Olive pollen has shown to cross-react with cypress pollen, pine pollen, mugwort, and birch in a study, where IgE binding to these pollen extracts was completely inhibited by extract of olive pollen. This showed that proteins of olive pollens share allergenic epitopes that are in common with the proteins of the other pollen extracts, and hence the cross-reactivity (30).
Cross-reactivity through IgE binding has been demonstrated among Italian cypress, white cypress pine, rye grass, ragweed, olive, birch, couch grass, plantain, lamb’s quarters, cocksfoot and wall pellitory (31).
Cross-reactivity has also been reported between peach and cypress pollen. This was evidenced in a case series of seven cypress pollen-allergic patients, who immediately after consuming peach developed OAS, urticaria or Quincke edema (32).