Objective—To evaluate a model for atopic dermatitis
(AD) and to measure the effect of sensitization in
Beagles genetically predisposed to produce high
serum concentrations of allergen specific IgE.
Animals—22 laboratory Beagles.
Procedure—Seventeen dogs were sensitized from
birth to 3 allergens (recombinant birch pollen,
Dermatophagoides pteronyssinus, and D farinae).
Five nonsensitized dogs from the same litters served
as controls. Clinical scoring, regular intradermal testing,
measurement of serum concentrations of allergen-specific IgE, and collection of biopsy specimens
of skin at 23, 32, and 43 weeks of age were performed.
Serial tissue sections were stained for identification
of IgE+ cells, mast cells and their subtypes, T-cells,
Langerhans cells, and major histocompatibility
complex class-II+ cells. At the age of 15 months,
dogs were continuously exposed to 2 µg of mite allergen/
g of dust.
Results—Sensitized dogs had positive intradermal
test reactions and significantly higher serum concentrations
of allergen specific IgE, compared with nonsensitized
dogs. In sensitized and nonsensitized
dogs, a significantly higher number of mast cells was
found at predilection sites, compared with the control
biopsy site. The number of mast cells at predilection
sites increased with age. Sensitization significantly
increased the number of epidermal Langerhans cells
by 23 weeks of age. The number of epidermal
Langerhans cells significantly increased in nonsensitized
dogs by 32 weeks of age. Clinical scoring only
revealed mild transient erythema in some dogs.
Conclusion and Clinical Relevance—Increases in concentrations of serum allergen-specific IgE and exposure to allergens is not
sufficient to induce clinical signs of AD in genetically
predisposed dogs. (Am J Vet Res 2002;63:1329–1336)