The adsorption of proteins on erythrocytes treated with tannic acid and subsequent hemagglutination by antiprotein sera.

Treatment of sheep erythrocytes with suitable concentrations of tannic acid render them capable of adsorbing certain protein molecules from solution in saline. Red cells which have adsorbed proteins in this way are agglutinated after washing by the homologous antiprotein sera, even by high dilutions. Through hemagglutination sera can be titrated for antibodies against antigens adsorbed on the cells exposed to tannic acid. Furthermore, small amounts of the antigens can be detected through their power to inhibit hemagglutination of the treated cells.