Meadow fescue grass pollen (Festuca elatior) (g4)

Meadow fescue grass pollen (Festuca elatior), also known as g4 allergen, consists of pollen grains from a perennial grass in the Poaceae family used for forage, turf, and soil stabilization, native to Eurasia and introduced in North America. Its primary allergens, including group 1 (Fes p 1), group 4 (Fes p 4), group 5 (Fes p 5), and group 13 (Fes p 13) proteins, trigger IgE-mediated type I hypersensitivity reactions upon inhalation, leading to allergic rhinitis, conjunctivitis, and asthma in sensitized individuals, accounting for 10-30% of global grass pollen allergies. These allergens cross-react extensively with other Pooideae subfamily grasses like timothy and ryegrass due to shared epitopes, particularly groups 1 and 4. Standardized extracts are used diagnostically via skin prick or intradermal testing (measured in Bioequivalent Allergy Units, BAU/mL) to confirm sensitivity and therapeutically via subcutaneous immunotherapy to induce tolerance by boosting blocking IgG/IgA antibodies and dampening IgE responses. No small-molecule drugs target it directly; treatment relies on allergen-specific immunotherapy, with risks of severe anaphylaxis requiring epinephrine readiness.

Other names

Festuca pratensisLolium pratenseFestuca arundinaceaMeadow fescue pollenFescue grass pollen

Immunotherapy: Increases IgG blocking antibodies, blunts seasonal IgE rise, reduces basophil reactivity and lymphocyte responsiveness to allergens