Polcalcin Phl p 7 (Phl p 7) (Phl p 7)

Polcalcin Phl p 7 is a highly potent calcium-binding protein found in the pollen of Phleum pratense (Timothy grass) [1, 3]. It belongs to the polcalcin family of panallergens and is characterized by two EF-hand motifs that facilitate its function as a calcium sensor [1, 6]. Structurally, Phl p 7 forms a unique domain-swapped homodimer, which significantly increases its allergenic potency by presenting multiple IgE-binding epitopes for cross-linking on mast cells and basophils [6, 8]. While considered a minor allergen due to its lower sensitization prevalence (approximately 10%) compared to major grass allergens, it serves as a critical biomarker for severe allergic phenotypes, including asthma and multi-sensitization across various plant species [1, 10]. In clinical practice, Phl p 7 is a target for allergen-specific immunotherapy (AIT), where it is administered in controlled doses to induce immune tolerance and shift the patient's immune response from a Th2-mediated allergic state to a Treg/Th1-mediated state [7, 10]. Therapeutic challenges include the risk of systemic allergic reactions during treatment and the high degree of cross-reactivity with other polcalcins, which can complicate diagnostic and treatment specificity [1, 7].

Other names

Phleum pratense allergen 7Calcium-binding pollen allergen Phl p 7Timothy grass pollen polcalcinProtein P7rPhl p 7

Allergen-specific immunotherapy (AIT) induces immune tolerance by promoting the production of allergen-specific IgG4 blocking antibodies, reducing IgE-mediated mast cell degranulation, and shifting the T-cell response from a Th2-type to a regulatory T-cell (Treg) and Th1-type response [7, 10].