Profilin-1 (Phl p 12) (Phl p 12)

Profilin-1 (Phl p 12) is a 14-kDa protein from Timothy grass (Phleum pratense) that belongs to the profilin family of actin-binding proteins (UniProt P35079). In its natural plant context, it regulates the dynamics of the actin cytoskeleton by binding to actin monomers and participating in intracellular signaling pathways (PMID: 15730164). Clinically, Phl p 12 is recognized as a major pan-allergen, meaning it exhibits high structural and sequence homology across a wide range of plant species, including birch (Bet v 2) and ragweed (Amb a 8) (IUIS Allergen Nomenclature). This high degree of conservation often leads to significant cross-reactivity, resulting in pollen-food allergy syndrome where sensitized individuals react to various fruits and vegetables. In the pharmaceutical industry, Phl p 12 is a key component in diagnostic assays and allergen-specific immunotherapy (AIT) products like GRAZAX and ORALAIR, which aim to desensitize patients by modulating their immune response from a Th2-mediated allergic phenotype to a Th1/Treg-mediated tolerant state (PMID: 19161593). Identifying sensitization to Phl p 12 is crucial for component-resolved diagnosis (CRD) to distinguish genuine primary grass pollen allergy from broad cross-sensitization.

Other names

Profilin-1Phl p XIIAllergen Phl p 12Timothy grass profilin

Allergen-specific immunotherapy (AIT) involves the administration of escalating doses of the allergen to induce peripheral T-cell tolerance, increase the production of regulatory T cells (Tregs), and stimulate the secretion of allergen-specific IgG4 'blocking' antibodies that inhibit IgE-mediated mast cell degranulation.