Rationale for Specific Immunotherapy of Grass Pollen Allergy with Extracts of Rye Pollen

In immunotherapy of grass pollen allergy, an extract of rye ( Secale cerebale ) is often included. The aim of this study was to investigate by skin prick test (SPT) and immunochemical methods whether rye pollen contains specific allergens justifying the use of this extract separately. Twenty grass pollen allergic patients were skin prick tested with a dialysed freeze-dried raw extract of rye pollen (Sc), timothy extract (Soluprick® SQ, 1 HEP) and two other rye extracts (Soluprick®). Sera from the patients were RAST-tested using Sc and timothy (Pp). CRIE was performed using Sc and rabbit-anti grass (aNG) antibodies. The antigenic relations between rye and common grasses were investigated by CLIE using Sc and aNG as references, and by RAST inhibition. The ability of aNG to absorb the allergen activity of Sc was also tested. Significant correlations were found between timothy and rye when compared by means of SPT and RAST. The immunochemical analyses did not reveal any rye antigens containing rye epitopes only. However, the possibility of rye antigens with several epitopes, of which at least one is specific for rye, could not be excluded. Clinical symptoms supposedly elicited by rye alone can be explained quantitatively by the strongly time-limited and concentrated natural exposition. Diagnosis and treatment can, however, be performed with extracts of common grasses.