MOLECULAR CHARACTERIZATION OF PHL P-II, A MAJOR TIMOTHY GRASS (PHLEUM-PRATENSE) POLLEN ALLERGEN

Grass pollen allergens belong to the most important and widespread elicitors of pollen allergy. Using serum IgE from a grass pollen allergic patient, a complete cDNA encoding a group II allergen was isolated from a timothy grass (Phleum pratense) pollen expression library. The deduced amino acid sequence of the Phlp II allergen shows an average sequence identity of 61% with the protein sequences determined for group II/III allergens from rye grass (Lolium perenne) and a sequence identity of 43% with the C-terminal portion of group I grass pollen allergens from different species. A hydrophobic leader peptide similar to leader peptides found in other major grass pollen allergens heads the deduced amino acid sequence, indicating that group II/III grass pollen allergens belong to a family of secreted proteins. Serum IgE specific for Phlp II, detected the protein exclusively in pollen and not in other plant tissues. The recombinant Phlp II was expressed in Escherichia coli and showed similar IgE-binding capacity as the natural allergen.