Type-1 hypersensitivity reactions to Malassezia pachydermatis extracts in atopic dogs.
OBJECTIVE
To investigate the potential allergenic role of the yeast Malassezia pachydermatis in dogs with clinical diagnosis of atopic dermatitis.


METHODS
5 clinically normal nonatopic dogs, 10 atopic dogs with cytologic evidence of Malassezia dermatitis, and 12 atopic dogs without cytologic evidence of Malassezia dermatitis.


METHODS
A crude yeast extract was produced by disrupting the cell wall of M pachydermatis. The crude extract and 8 of its fractions, which were generated by fractionation in a high-performance liquid chromatography column, were injected along with 46 commercial allergens for intradermal allergy testing of normal and atopic sample populations. Significant difference between atopic populations was evaluated, using a threshold concentration of crude yeast extract that failed to induce wheal-and-flare responses in normal nonatopic dogs.


RESULTS
Atopic dogs with cytologic evidence of Malassezia dermatitis had significantly greater wheal-and-flare reactions to intradermal injection of crude extract of M pachydermatis than did atopic dogs without cytologic evidence of Malassezia dermatitis.


CONCLUSIONS
It is concluded that M pachydermatis is capable of promoting type-1 hypersensitivity reactions in dogs with an atopic dermatitis phenotype.


CONCLUSIONS
Currently, Malassezia dermatitis is principally managed by use of antifungal chemotherapy. Because the yeast appears to be a contributing allergen in dogs with atopic dermatitis, hyposensitization with M pachydermatis extracts may offer a future alternative to extended or repeated episodic administration of antifungals for extended control of recurrent infections.
Morris
D O
DO
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing 48824-1314, USA.
Olivier
N B
NB
Rosser
E J
EJ
D000485:Allergens; D000818:Animals; D000946:Antigens, Fungal / Q000276:immunology; D003876:Dermatitis, Atopic / Q000276:immunology / Q000662:veterinary*; D004283:Dog Diseases / Q000276:immunology*; D004285:Dogs; D006967:Hypersensitivity; D008290:Malassezia / Q000276:immunology*; D012882:Skin Tests / Q000662:veterinary
D000485:Allergens; D000946:Antigens, Fungal