Allergenic profile to Phleum pratense and immunological changes induced after grass allergen-specific immunotherapy.

Background: The introduction of molecular diagnoses has provided evidence of the existence of several different allergenic profiles in grass-sensitised individuals, reflecting the large number of allergens involved. This methodology has become a potent tool for a correct diagnosis and for the selection of the most appropriate immunotherapy. Based on these concepts, the objectives of this study were to determine the sensitisation profile of a grass-allergic population, and to treat them with specific immunotherapy.

Methods: Patients suffering from rhinitis and/or asthma associated with grass pollen were recruited. The active group was treated with depigmented-polymerised allergenic extract of mixed grass pollen. sIgE and sIgG4 to Phleum pratense, and to its individual components (Phl p 1, 2, 4, 5b, 6, 7, 11 and 12) were determined at the beginning and end of the study.

Results: The inclusion criteria were fulfilled by 139 individuals (36 in the control group and 103 in the active group). Phl p 1 (96.4%) and Phl p 4 (91.2%) were the most recognised allergens, and 15.3% of individuals had positive IgE to cross-reactive carbohydrate determinants. Levels of antigen-specific IgG4 increased significantly after treatment, and the IgE/IgG4 ratio decreased significantly in all allergens after receiving allergen-specific immunotherapy. Non-significant differences were observed in the control group.

Conclusions: A high percentage of sensitisation to Phl p 4 was observed. Immunological efficacy was studied by measuring sIgG4 levels and the IgE/IgG4 ratio before and after treatment. Sensitisation profiles should be taken into consideration to prepare the most appropriate immunotherapy containing all the relevant and needed allergens.