Immunoglobulin E (IgE) specific for Phleum pratense allergen 1 (Phl p 1) and Phleum pratense allergen 5 (Phl p 5) (Phl p 1/5-specific IgE)

Immunoglobulin E (IgE) antibodies specific for Phl p 1 and Phl p 5 are the primary immunological mediators of Timothy grass (Phleum pratense) pollen allergy, a major cause of seasonal allergic rhinitis and asthma (Valenta et al., 1992, PubMed: 1379453). Phl p 1 and Phl p 5 are recognized as major allergens because they elicit an IgE response in the vast majority of grass pollen-allergic individuals (WHO/IUIS Allergen Nomenclature). These antibodies bind to high-affinity FcεRI receptors on mast cells and basophils, sensitizing the immune system to subsequent pollen exposure. Upon re-exposure, the allergens cross-link the surface-bound IgE, triggering the rapid release of inflammatory mediators such as histamine, which leads to clinical symptoms like sneezing, congestion, and bronchospasm (Bousquet et al., 2008, PubMed: 18331513). Therapeutic interventions include the use of anti-IgE monoclonal antibodies like Omalizumab, which sequester circulating IgE to prevent receptor binding (Xolair Prescribing Information). Additionally, allergen-specific immunotherapy (AIT) utilizes Phl p 1 and Phl p 5 extracts to shift the immune response toward tolerance, typically characterized by an increase in protective IgG4 antibodies and a reduction in the IgE-mediated allergic cascade (Durham et al., 1999, PubMed: 10446080).

Other names

Timothy grass pollen-specific IgEAnti-Phl p 1 IgEAnti-Phl p 5 IgEGrass pollen-specific IgE antibodies

Omalizumab binds to the Cε3 domain of circulating IgE, preventing its interaction with the high-affinity IgE receptor (FcεRI) on mast cells and basophils. Allergen-specific immunotherapy (AIT) involves the administration of Phl p 1 and Phl p 5 allergens to induce peripheral T-cell tolerance and promote the production of allergen-specific IgG4 antibodies, which act as blocking antibodies to prevent IgE-mediated mast cell activation.