Jun a 1 (Pectate lyase) (Jun a 1)

Jun a 1 is the primary major allergen found in the pollen of Juniperus ashei (Mountain cedar), a member of the Cupressaceae family (UniProt P43213). It is a 43 kDa protein that functions biologically as a pectate lyase, an enzyme involved in the degradation of pectin within plant cell walls to facilitate pollen tube growth (IUIS Allergen Nomenclature). In sensitized individuals, Jun a 1 is a potent inducer of Type I hypersensitivity, leading to 'Cedar Fever,' which manifests as severe allergic rhinitis, conjunctivitis, and asthma during the winter pollination season (Ramirez, 1984). The protein exhibits high structural homology and IgE cross-reactivity with other Cupressaceae allergens, such as Cry j 1 from Japanese cedar and Cup a 1 from Arizona cypress (Gadermaier et al., 2004). Therapeutic intervention primarily involves allergen-specific immunotherapy (AIT), which utilizes standardized extracts of Jun a 1 to induce immunological tolerance and increase the production of protective IgG4 antibodies (Nelson et al., 1997). Additionally, the interaction between Jun a 1 and allergen-specific IgE is indirectly targeted by monoclonal antibodies like Omalizumab, which bind to circulating IgE to prevent its attachment to mast cells and subsequent degranulation (Bousquet et al., 2005).

Other names

Jun a IMountain cedar major allergen 1Pectate lyaseCupressaceae Group 1 allergensJuniperus ashei allergen 1

Allergen-specific immunotherapy (AIT) involves the administration of increasing doses of Jun a 1 to induce peripheral T-cell tolerance, shifting the immune response from a Th2 to a Th1/Treg profile and increasing allergen-specific IgG4 (Nelson et al., 1997). Monoclonal antibodies like Omalizumab bind to the Fc region of free IgE, preventing its interaction with the high-affinity IgE receptor (FcεRI) on mast cells and basophils, thereby inhibiting the allergic cascade triggered by Jun a 1 (Bousquet et al., 2005).