Rye allergy

Rye pollen allergy: Rye pollen has the highest allergenic potency among grasses. They are the most important trigger of a grass pollen allergy (see below grass pollen and cereal pollen) and therefore the most frequent trigger of a pollinosis. The allergenic potency of rye pollen is about 5 times higher than that of wild grass pollen. Rye is the only cereal whose pollen is present in large quantities in the air (up to 4 million pollen are released per plant). Pollen flies in May and June. Size: 52-65 µm.

There is a clear difference in allergenic potency between rye pollen and rye flour.

Allergy to rye flour: Rye flour, like wheat flour, can cause respiratory allergies. Rye flour has a lower allergenic potency than wheat flour. Only a massive, long-term exposure leads to sensitisation. Rye flour is the third most common allergen in the baking industry. As with wheat, the most important allergens are alpha-amylase inhibitors.

One of the main allergens of rye is Sec c 1 (other allergens are Sec c 5; Sec c 20 and Sec c 38). Sec c 1 was already characterized in 1996 by Garcia-Casado. Its structure belongs to the group of amylase inhibitors (Jäger L 2001). About 80% of rye flour allergy sufferers are sensitized by Sec c 1. Proven positive skin tests on rye flour (e.g. in grass pollen allergy sufferers) are without clinical relevance (heated rye flour is usually tolerated without reaction). Cross-reactivity is found between the allergens of rye pollen and rye flour.

Further allergens are:

Sec c 5 Secale cereale

Sec c 20 Secale cereale (gamma-secalin); this allergen appears to play a role in wheat-dependent exercise-induced anaphylaxis a pathogenetic role.

Sec c 38 Secale cereale: Sec c 38 is a dimeric alpha-amylase -/trypsin- inhibitor which plays a pathogenetic role in baker's asthma (in one study 71% of asthmatics were reactive to this allergen).

Cross-reactions to other cereal flours are common in rye sensitised people; also between rye pollen and other grass species. However, rye specific sensitisations can also occur.

1. García-Casado G et al.(1996) Rye flour allergens associated with baker's asthma. Correlation between in vivo and in vitro activities and comparison with their wheat and barley homologues. Clin Exp Allergy 26:428-435.

2. Jäger L et al (2001) Food allergies and intolerances. Urban & Fischer Publishing House Munich, Jena S 119-120

3. Letrán A et al (2008) Rye flour allergens: an emerging role in baker's asthma. Rye flour allergens: an emerging role in baker's asthma. On J Ind Med 51:324-328.