Mouse strain specificity of the IgE response to the major allergens of Phleum pratense.

ABSTRACT

BACKGROUND: IgE immune responses against major allergens from Phleum pratense in low- and high-responder mouse strains were compared and the influence of alum was assessed, in order to evaluate the effect of the genetic background and adjuvants on IgE reactivity in a mouse model for P. pratense allergy. METHODS: Different mouse strains and F1 offspring were sensitized with P. pratense pollen extract. Serum IgE levels, the induction of specific IgE antibodies and immediate cutaneous hypersensitivity reactions were monitored by ELISA, Western blot and a skin test, respectively. RESULTS: All mouse strains investigated mounted an IgE response and exhibited a positive skin test to pollen extract. Differences were seen in the level of total serum IgE and in specific IgE reactivity to different major allergens of P. pratense. Notable differences were seen in IgE reactivity and immediate hypersensitivity against Phl p 1, which were only observed in SJL/j mice. The foremost influence of alum was on total IgE production levels. CONCLUSIONS: Alum is not necessary as an adjuvant to elicit IgE reactivity against the clinically relevant allergens of P. pratense, since even low-responder mouse strains mounted a hypersensitivity reaction after sensitization without the adjuvant using otherwise identical sensitization strategies. Moreover, when analyzing the allergenicity of a compound, the hypersensitivity response of different mouse strains should be considered, as implicated by the differential results obtained for IgE reactivity against Phl p 1. Lastly, a genetic component may be involved in IgE reactivity to Phl p 1.