Allergens of Mammalian Origin: III. Properties of a Major Feline Allergen

A purified fraction of cat pelt extract was prepared and subjected to electrophoresis in 7% acrylamide gel. The bulk of the allergenic activity was recovered from the prealbumin portion of the gel that contained a single band of protein (band B). Antiserum to band B reacted with both band B and albumin; after absorption with albumin, only antibody against band B could be detected. Electrophoresis of band B protein in 10% acrylamide gel resolved four protein bands; one of these bands was associated with the bulk of allergenic activity and reacted with absorbed antiserum to band B. The absorbed antiserum (anti-allergen antiserum) reacted in gel diffusion with a single component of crude cat pelt extract; this component had the molecular size characteristics of allergen. Anti-allergen antiserum removed significant amounts of allergenic activity from both crude cat pelt extract and purified fractions of cat pelt extract. It is proposed that the allergen defined by this antiserum be designated cat allergen 1. The radioallergosorbent test was modified so as to provide an assay for allergen. The modified test provided a useful supplement to the skin test as an assay for allergen and showed that, of various cat tissue extracts, pelt extract was the most abundant source of allergenic activity. Extract of cat brain also contained significant amounts of allergen.