Major allergen Pla a 1 (Pla a 1)

Pla a 1 is the primary major allergen found in the pollen of the London plane tree (Platanus acerifolia), which is widely planted in urban environments. It is a 18-kDa glycoprotein that belongs to the invertase inhibitor-like protein family and is recognized by IgE antibodies in over 90% of plane tree-allergic patients (Lauer et al., 2004). The protein's biological function in the plant is likely related to the regulation of carbohydrate metabolism or defense mechanisms through the inhibition of invertase enzymes (UniProt, 2024). In humans, Pla a 1 is a potent trigger for Type I hypersensitivity, leading to clinical manifestations such as allergic rhinitis, conjunctivitis, and asthma (Pazos-Castro et al., 2019). From a therapeutic perspective, Pla a 1 is the central component in allergen-specific immunotherapy (AIT) for plane tree pollinosis, where it is used to desensitize patients and shift the immune response toward tolerance (WHO/IUIS, 2024). Standardized extracts containing Pla a 1 are used both for diagnosis via skin prick testing and for long-term subcutaneous or sublingual immunotherapy.

Other names

Platanus acerifolia allergen 1London plane tree major allergenInvertase inhibitor-like protein Pla a 1

Induction of immune tolerance through repeated exposure, leading to a shift from Th2-mediated allergic response to Th1 and regulatory T-cell (Treg) responses, and the production of IgG4 blocking antibodies (Pazos-Castro et al., 2019)