Phleum pratense pollen allergen extract

Phleum pratense pollen allergen extract is a biological substance derived from the pollen of Timothy grass, which is a primary source of seasonal aeroallergens globally [FDA, 2014]. The extract contains a complex mixture of proteins, including major allergens like Phl p 1 and Phl p 5, which are responsible for triggering Type I hypersensitivity reactions in sensitized individuals [UniProt, 2023]. In clinical pharmacology, this extract is not a traditional molecular target such as a receptor or enzyme; instead, it serves as the active pharmaceutical ingredient in allergen-specific immunotherapy (AIT) [StatPearls, 2023]. The therapeutic goal of using this extract is to induce immunological tolerance in patients suffering from grass pollen-induced allergic rhinitis and conjunctivitis [NIH, 2021]. Its mechanism involves modulating the immune system to shift from a Th2-dominated allergic response to a Th1 and regulatory T-cell (Treg) profile [Journal of Allergy and Clinical Immunology, 2014]. This shift promotes the production of allergen-specific IgG4 "blocking antibodies," which compete with IgE for allergen binding and prevent mast cell degranulation [PubMed, 2011]. Commercial products utilizing this extract include sublingual tablets such as Grastek and Grazax, which are administered daily to reduce allergic symptoms and the need for rescue medications [EMA, 2006]. While effective, the use of this extract carries safety risks, most notably the potential for localized oral reactions or systemic allergic responses, including anaphylaxis [Mayo Clinic, 2023].

Other names

Timothy grass pollen extractPhl p allergen extractTimothy grass pollen allergenGrass pollen allergen extract

Allergen-specific immunotherapy (AIT) works by inducing peripheral T-cell tolerance, increasing the production of regulatory T cells (Tregs) and IL-10, and promoting a shift from a Th2 to a Th1 immune response. It also stimulates the production of allergen-specific IgG4 antibodies, which act as "blocking antibodies" to prevent IgE-mediated mast cell degranulation [StatPearls, 2023; JACI, 2014].