Much desired - and yet feared: the early summer .... means an unpleasant grass pollen allergy for every 5th among us

Most of us enjoy the first shafts of sunshine and the blooming meadows, however for every 5th among us this means - watery eyes, sneezing and runny noses. 20% of the population suffers from grass pollen allergy.

Which grasses are the main triggers for grass pollen allergy?

Especially tall-growing grasses in forage meadows, such as timothy grass (Phleum pratense), common knapweed (Dactylis glomerata), smooth oat (Arrhenatherum elatius), Italian ryegrass (Lolium multiflorum), German ryegrass (Lolium perenne), and Bermuda grass (Cynodon dactylon) are highly allergenic. They are found almost everywhere. They can be found not only in meadows and pastures, but even along roadsides and in forest clearings. (1)

Symptoms affect the respiratory system - rhinitis (sneezing, runny and stuffy nose), conjunctivitis (itchy, watery, red eyes), and asthma (coughing, wheezing, chest tightness, difficulty breathing). Clinical manifestations can also affect the skin:

• Itching

• urticaria (hives)

• eczema (atopic dermatitis)

What to do if grass pollen allergy is suspected?

Diagnosis includes a comprehensive clinical anamnesis, skin tests, determination of allergen-specific IgE antibodies and provocation tests. Extracts often differ in their qualitative as well as quantitative allergen composition.

However, allergen components help to distinguish between positive results due to sensitisation to specific grass pollen allergens or cross-reactivity with food, herb or tree pollens. ALEX contains a very broad spectrum of grass pollen allergens and is therefore recommended to enable accurate diagnosis. Both major allergens (Cyn d 1, Lol p 1, Phl p 1, Phl p 5, Phl p 6) and minor allergens (Phl p 7, Phl p 12) are included on ALEX. Allergens such as Phl p 1, Phl p 2, Phl p 4, Phl p 5, Phl p 6, Phl p 11 are marker allergens for primary sensitisation to grass pollen, whereas IgE reactivity to Phl p 7 (Polcalcin) and Phl p 12 (Profilin) indicates cross-reactivities. Cross-reactivity between Polcalcins can be observed between grass-, tree- and weed- pollen, such as Phl p 7 and Aln g 4 for instance. (2) However, Polcalcins are not found in plant-based foods. In contrast, Profilins are cross-reactive not only in its biological family but also beyond that. Profilins are cross-reactive within grass-, tree and weed pollen but also with Profilins from plant-based foods, such fruits, legumes, nuts, seeds, cereals, and spices. (3) These cross-reactivities can be tracked using ALEX results and treatment recommendations can be advised.

An additional, special feature of ALEX is the automatic blocking of clinically irrelevant IgE antibodies against cross-reactive carbohydrate determinants (CCDs). Phl p 1 and Phl p 4 are CCD-bearing proteins. Especially, Phl p 4 is a glycosylated protein with cross-reactive carbohydrate determinants (CCDs) that has a high frequency of IgE reactivity and low allergenicity because sentitised individuals develop IgE antibodies against the poorly antigenic CCDs. (4)

Some case studies show how helpful this automatic CCD blocking of the ALEX multiplex test is in the daily routine of clinicians. In a specific case of a supposedly polysensitised patient, the number of falsely elevated results was reduced from 110 to 10 (Link to the case study: storyblok). From this example, it is very clear that with CCD blocking, the results fit the clinical picture much better, thus significantly reducing the interpretation burden of the physician. At the same time, there is often the good news for patients that foods that had to be avoided because of previous false positive test results due to cross-reactivity with pollen allergens can be reintroduced into the diet. In a recent publication, Heffler et al. performed a comparison between the results of ALEX® and ImmunoCAP® ISAC for specific allergen components and concluded a good correlation between ALEX® and ISAC. However, the use of CCD inhibitors in ALEX® Multiplex tests reduces the binding of IgE to CCDs. In particular, polysensitised patients and patients with pollen-food syndrome will have a real advantage due the combination of the second and third levels of allergy diagnostics in the same chip. (5)

What can give me quick relief?

For acute symptoms, topical medications can provide rapid help. Topical medications act only on the part of the body to which they are applied. These include nasal sprays or eye drops with ingredients such as antihistamines, corticosteroids and vasoconstrictors. In contrast, antihistamine tablets act as systemic medications on the entire body.

As a long term solution for grass pollen allergy, there is only one treatment option available, hyposensitisation by immunotherapy. Phl p 1 and Phl p 5 act as marker allergens indicating a genuine grass pollen allergy and are indicators for immunotherapy. (6) ALEX provides detailed and accurate results at the molecular level, which can be helpful for the selection of an appropriate allergen-specific immunotherapy (AIT).

ALEX - The key to accurate grass pollen allergy diagnosis.

References

(1) DOI: 10.1016/S1808-8694(15)31005-3

(2) DOI: 10.18176/jiaci.0054

(3) DOI: 10.1016/s0091-6749(97)70249-5

(4) DOI: 10.1016/j.jaci.2020.04.011

(5) DOI: 10.1186/s40413-018-0186-3

(6) DOI: 10.2332/allergolint.11-OA-0372