Major allergen Par j 2 (Par j 2)

Par j 2 is a major allergen from the pollen of Parietaria judaica, a Mediterranean weed commonly known as pellitory-of-the-wall (UniProt: P55959). It belongs to the non-specific lipid-transfer protein (nsLTP) family, characterized by a compact structure stabilized by four disulfide bridges, which confers high stability against heat and proteolysis (PubMed: 10851151). In the plant, Par j 2 is involved in lipid transport and defense mechanisms, but in humans, it is a potent inducer of Type I hypersensitivity (WHO/IUIS Allergen Nomenclature). It is one of the primary drivers of pollinosis in Mediterranean regions, contributing significantly to allergic rhinitis and bronchial asthma (PubMed: 15584995). Therapeutic approaches involving Par j 2 focus on allergen-specific immunotherapy (AIT), where controlled exposure to the protein or its derivatives aims to induce peripheral T-cell tolerance and increase protective IgG4 antibodies (PubMed: 11344355). While effective, the use of whole allergen extracts carries a risk of systemic IgE-mediated reactions, leading to research into hypoallergenic variants or recombinant forms for safer treatment (PubMed: 12639122). Diagnostic applications utilize Par j 2 to identify patients sensitized to Parietaria pollen, allowing for more targeted treatment strategies (PubMed: 15584995). The protein's high cross-reactivity with other nsLTPs from different plant species makes it a critical component in understanding and managing complex pollen-food allergy syndromes (PubMed: 21213740).

Other names

Non-specific lipid-transfer protein 2nsLTP 2Parietaria judaica allergen 2Par j 2.0101

Allergen-specific immunotherapy (AIT) utilizes the allergen to desensitize the immune system by inducing regulatory T cells (Tregs), shifting the immune response from a Th2 to a Th1 profile, and promoting the production of blocking IgG4 antibodies (PubMed: 11344355).