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  • Author or Editor: Thomas J. Grier x
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Abstract

Objectives

To determine whether flea extract could be determined (via ELISA) to share allergenic epitopes with other insects, and to determine whether sera with different reactivities to insect extracts have different cross-reactivity patterns.

Sample Population

69 canine serum samples that were selected from samples submitted for routine ELISA allergy testing and had previously been found to have high reactivities to flea.

Procedure

Each serum sample was assessed by means of a direct ELISA for IgE binding to 11 common insects. Samples that were reactive primarily to flea extract alone were designated pool 1, samples that were reactive to small numbers of insects were designated pool 2, and samples that were reactive to all or almost all insects were designated pool 3. Samples that did not have any apparent patterns of cross-reactivity were not included in the rest of the study. Inhibition ELISA techniques were used with the 3 serum pools to determine whether multiple insect extracts inhibited reactivity on flea-coated ELISA plates. Those extracts were used to coat ELISA plates, and reciprocal inhibition studies were then performed.

Results

Black fly, black ant, and cockroach extracts were capable of > 50% inhibition of flea solid-phase IgE binding with all 3 serum pools. In the ELISA inhibition studies, flea extract was able to inhibit IgE binding to each extract with all pools, confirming reciprocal inhibition.

Conclusions

Inhibition of IgE binding to solid-phase flea antigen by black ant, black fly, and cockroach extracts suggested sharing of allergenic epitopes among these species. Reciprocal inhibition studies further confirmed these findings. These results indicated in vitro cross-reactivity between flea, black ant, black fly, and cockroach extracts. These results need to be further investigated in vivo.

Clinical Relevance

It is possible that dogs may become sensitized to fleas via exposure to other insects, and that flea allergenic dogs may have signs of pruritus, in the absence of fleas, if exposed to cross-reactive insects. (Am J Vet Res 1996;57:1000–1005)

Free access
in American Journal of Veterinary Research

Objective

To compare cutaneous reactivity to insect and arachnid allergens in clinically normal (control) and allergic dogs in the southeastern United States.

Design

Prospective, controlled study.

Animals

26 clinically normal dogs and 82 allergic dogs from the southeastern United States.

Procedure

Intradermal skin testing with various dilutions of 13 insect and arachnid allergens was performed on control dogs to establish skin threshold concentrations (ie, concentrations to which < 25% of the dogs had positive reactions). These established threshold concentrations were then used to test allergic dogs for reactivity. Prevalence of single and multiple insect and arachnid reactions were determined.

Results

Flea allergen was the only allergen that caused a significantly higher prevalence of positive reactions in allergic dogs than in control dogs.

Clinical Implications

Flea hypersensitivity is the most important arthropod hypersensitivity in dogs. The importance of reactivity to insect and arachnid allergens other than flea allergen can be determined only when prevalence of positive reactivity has been determined in an appropriate regional control group of dogs. (J Am Vet Med Assoc 1996;209:1431–1434)

Free access
in Journal of the American Veterinary Medical Association