Timothy grass pollen allergen Phl p 5a (Phl p 5a)

Timothy grass pollen allergen Phl p 5a is a major protein allergen derived from the pollen of Phleum pratense, widely recognized as one of the most potent triggers of seasonal allergic rhinitis and asthma globally. It belongs to the group 5 grass pollen allergens, which are characterized by high IgE-binding prevalence, with over 80% of grass-pollen-allergic individuals showing sensitivity to this specific protein (UniProt: Q40240; WHO/IUIS Allergen Nomenclature). Biologically, Phl p 5a is a highly soluble protein released rapidly from hydrated pollen grains, facilitating its interaction with the respiratory mucosa and subsequent cross-linking of IgE on mast cells and basophils. This interaction triggers the degranulation of inflammatory mediators responsible for hay fever symptoms. In clinical practice, Phl p 5a is a critical target for allergen-specific immunotherapy (AIT), where it is administered in standardized extracts (such as Grazax or Oralair) to desensitize the immune system and induce long-term tolerance (PubMed: 12519337). Monitoring Phl p 5a-specific IgE and IgG4 levels is essential for diagnosing sensitivity and evaluating the efficacy of immunotherapy treatments.

Other names

Major pollen allergen Phl p 5.0101Phl p VPhleum pratense allergen 5aGroup 5 grass pollen allergen

Allergen-specific immunotherapy (AIT) to induce peripheral T-cell tolerance, shift the immune response from Th2 to Th1/Treg, and increase protective allergen-specific IgG4 antibodies.