Phleum pratense allergen (Phl p)

Phleum pratense allergens, derived from the pollen of Timothy grass, are a group of potent proteins that represent a primary cause of seasonal allergic rhinitis (hay fever) and asthma worldwide [11, 19]. These allergens are categorized into several groups, with Phl p 1 (a beta-expansin) and Phl p 5 (a ribonuclease-like protein) being the major components responsible for sensitization in over 80% of grass-pollen-allergic individuals [9, 10, 19]. In sensitized patients, these proteins trigger type I hypersensitivity reactions by cross-linking IgE antibodies on the surface of mast cells and basophils, leading to the release of inflammatory mediators like histamine [16, 18]. Beyond their role as environmental triggers, Phleum pratense allergens are the central therapeutic targets and active ingredients in allergen-specific immunotherapy (AIT) [4, 6]. Therapeutic extracts, such as those found in sublingual tablets like Grastek or Oralair, are administered to induce immune tolerance [6, 13]. The mechanism involves shifting the patient's immune response from an allergic Th2 profile to a tolerant Th1 and regulatory T cell (Treg) profile, accompanied by the production of protective IgG4 blocking antibodies [1, 4, 10].

Other names

Timothy grass pollen allergenPhleum pratense pollen allergenTimothy grass allergen extractPoaceae grass allergenGrass group 1/5 allergen

Induces allergen-specific immune tolerance by shifting the immune response from a Th2-mediated allergic profile to a Th1/Treg-mediated profile, increasing blocking IgG4 antibodies, and reducing IgE-mediated mast cell activation [1, 4, 10].