rPhl p 7
Phl p 7 is a minor allergen of Phleum pratense pollen, recognized by IgE antibodies from 10-15% of grass pollen sensitized subjects. It is 8.6 kD two-EF-hand Ca2+-binding protein with 68-93% amino acid sequence identity to homologous pollen proteins of Brassica species, Alnus glutinosa, Olea europea, Betula verrucosa and Cynodon dactylon. Cloning and molecular analysis of Phl p 7 was reported by Niederberger et al. (1).

Single components from timothy grass, Phleum pratense, are available for specific IgE testing, produced either with recombinant technique or as purified native proteins. As an alternative the next generation of immunotherapy may be based on recombinant allergen components, possibly modified to reduce the risk of anaphylaxis. If the sensitization profile to e.g. timothy is known, only those components to which the patient is actually sensitized should be relevant for therapy. This would eliminate the risk that the therapeutic reagent induces IgE antibodies to additional components. The single components of timothy in specific IgE tests may also be used for monitoring immunotherapy with the natural extract.

rPhl p 7,  a two-EF-hand Ca2+-binding protein is likely to cross-react with pollen proteins from most plants, in particular with other grass species, trees of the Fagales order, olive and weeds. rPhl p 12;  profilin from timothy is a so-called pan-allergen that may be involved in cross-reactivities seen between many different plants, including plant-derived foods (examples of other profilins: Hev b 8 = profilin in Latex (Hevea braziliensis), Bet v 2 = profilin in Birch (Betula verrucosa)). However, both rPhl p 7 and rPhl p 12 have shown to be minor allergens and the clinical consequence of the speculated cross-reactivity with other plants is probably not of major importance, but cannot be excluded.