Mouse Strain Specificity of the IgE Response to the Major Allergens of <i>Phleum pratense</i>

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.

Reduced Allergenic Potency of VR9-1, a Mutant of the Major Shrimp Allergen Pen a 1 (Tropomyosin)

“…To identify the IgE-binding epitopes (shortest peptide with maximal IgE Ab reactivity) 5-to 15-aa-long peptides with offsets of one or two residues were synthesized spanning the previously identified main IgE-binding regions of Pen a 1 (region 1, Pen a 1 [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] ; region 2, Pen a 1 85-105 ; region 3, Pen a 1 133-153 ; region 4, Pen a 1 187-201 ; region 5, Pen a 1 247-284 ) (2). These peptide libraries were probed with patients' sera for specific IgE Abs as described previously (2).…”

“…1A) were identical for all four subjects tested (Pen a 1 [43][44][45][46][47][48][49][50][51][52][53][54][55] ), VHNL QKRMQQLEN) and consisted of 13 aa residues. Pen a 1 [43][44][45][46][47][48][49][50][51][52][53][54][55] differed at nine or 10 aa positions from homologous vertebrate tropomyosin sequences. Thus, the sequence identity was very low (23-31%), and the sequence similarity ranged from 39 -54%.…”

“…The individual Pen a 1 epitopes differed in two or three amino acid positions from those of the homologous vertebrate sequences. Thus, sequence identity (73%) and similarity (87-100%) of this epitope to homologous vertebrate sequences were much higher than those of Pen a 1 [43][44][45][46][47][48][49][50][51][52][53][54][55] .…”

“…Peptides were tested for IgE binding with sera from 18 shrimp-allergic subjects. Based on frequency and intensity of IgE binding, five major allergenic regions were identified: region 1 (Pen a 1 [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] ), region 2 (Pen a 1 ), region 3 (Pen a 1 ), region 4 (Pen a 1 [187][188][189][190][191][192][193][194][195][196][197][198][199][200][201] ), and region 5 (Pen a 1 ). The IgE binding regions seemed to occur at regular intervals in the molecule spaced approximately every sixth heptad (approximately every 42 aa), suggesting some relation with the coiled-coil structure of tropomyosin.…”

Airway hyperresponsiveness is associated with activated CD4+ T cells in the airways

“…When the antigen ovalbumin (OVA) is used, BALB/c and AKR (8) mice develop AHR, whereas others, such as the C57BL/6 and 129/Sv strains, are hyporesponsive (8,41). Although this strain-dependent responsiveness has been linked to differences in IgE production and eosinophil recruitment to the lung (8,39,41), such links are tenuous as these surrogate immunological markers are often discordant with AHR (13,47).…”