Phenol amplifies complement-fixing activity and induces IgG-precipitating activity in grain-dust extract

The use of phenol as a preservative in extracts of grain dust was found to be associated with an amplification of complement-fixing activity and the appearance of IgG-precipitating activity. Both activities were absorbed by IgG, suggesting that they were due to a single material. Phenol itself neither fixed complement nor formed a precipitate with IgG. 14C-labeled phenol was incorporated into the IgG precipitating material. Both the amplification of complement-fixing activity and the appearance of IgG-precipitating activity in phenol-containing grain-dust extract were dependent on the presence of air and were inhibited by heating the extract before phenol addition. One interpretation of these results is that a component of grain-dust extract, possibly an enzyme, oxidatively modifies phenol to a form that fixes complement and precipitates IgG. The modified material demonstrates properties of a polyphenol (tannin).