g212 rPhl p 12 Profilin, Timothy

Allergens within Grass Pollens

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  • Latin name: Phleum pratense
  • Source material: An E. coli strain carrying a cloned cDNA encoding Phleum pratense allergen Phl p 12.
rPhl p 12
Phl p 12 is a 14 kD pollen profilin. It has the characteristics of a minor allergen, binding IgE antibodies from approximately 20% of grass pollen allergic subjects. Profilin is a ubiquitous protein in all eukaryotic organisms and Phl p 12 shares >75% sequence identity with profilins of a wide range of species, from pollen as well as various plant-derived foods and latex. (1-2) The sequence identity between Phl p 12 and animal profilins ranges between approximately 30% and 45%. Immunological cross-reactivity among pollen profilins and profilins of plant-derived foods is well documented.

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.

References:

    1. Asturias, J. A., Arilla, M. C., Bartolomé, B., Martinez, J., Martinez, A. and Palacios, R. (1997). Sequence polymorphism and structural analysis of timothy grass pollen profilin allergen (Phl p 11). Biochem. Biophys. Acta 1352:253-257.
    2. Valenta, R., Ball, T., Vrtala, S., Duchene, M., Kraft, D. and Scheiner, O. (1994). cDNA cloning and expression of timothy grass (Phleum pratense) pollen profilin in Escherichia coli: comparison with birch pollen profilin. Biochem. Biophys. Res. Commun. 199:106-118.

2002



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