Immunoglobulin A Identified as New Cat Allergen

Airborne IgA from dried saliva may cause IgE response in humans sensitized to cat dander

FRIDAY, April 6 (HealthDay News) -- Cat immunoglobulin A is a newly identified allergen that stimulates IgE production in patients with cat allergies, according to a report in the March issue of the Journal of Allergy and Clinical Immunology.

Justus Adédoyin, M.Sc., of Karolinska University Hospital in Stockholm, Sweden, and colleagues used protein electrophoresis and ELISA-based assays to test the sensitivity of subjects with cat allergies to purified feline IgA.

The investigators found that 38 percent of sera from patients sensitized to cat dander cross-reacted with purified feline IgA or IgM. The results show that reactivity was directed mainly to the glycosylated IgA heavy chain and was enhanced by cross-linking with calf intestine alkaline phosphatase. Indirect ELISA identified IgE as the primary cross-reacting human immunoglobulin.

The authors suggest that IgA is released as airborne particles from dried saliva on the cat's fur. "This new group of cross-reactive carbohydrate IgE epitopes should be taken into consideration when diagnosing patients with suspected animal allergy," the authors write.

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