Characterization of Allergenic Determinants on the C-Terminal Region of the r-Lol p 1

Abstract

Current forms of allergy diagnosis and therapies are based on the use of natural allergenic extracts. Such extracts represent mixtures of more than 50 different molecules, mostly proteins. Despite strong evidence that higher therapeutic efficacy may be achieved with purified extracts, the purification of multiple allergic components from a given extract is a fastidious and sometimes an impossible task. However, the use of re-combinant allergens may be an alternative to overcome this problem. To date, cDNA from several allergic proteins have been cloned and the corresponding recombinant allergens have been synthesized. The characterization of these allergens by cDNA technology provides important information about the primary structure of allergens and about the similarities with already known proteins. In the case of ryegrass pollen (Lolium perenne), which is responsible for a large portion of grass pollen allergies worldwide, at least three major classes of allergenic proteins (Lol p 1, Lol p 2 and Lol p 3)(1— 5) have been isolated and characterized. The major allergen, Lol p 1, is a glycoprotein of about 32 kDa and represents the major IgE-binding protein, as 85–90% of ryegrass sensitive patients react against this protein. Moreover, elevated levels of Lol p 1-specific IgE have been detected in the sera of up to 95% of grass pollen sensitive patients. Recently, the cDNA of two isoforms of Lol p 1 have been sequenced and found to encode a protein of the same size (240 residues). However a lack of information still persists about the IgE-binding epitopes on the Lol p 1. The present study has therefore further characterized the IgE binding epitopes on the rLol p 1 using recombinant technology, mAbs, and synthetic peptides.