An Improved Serologic Method for the Determination of the Precipitative Titers of Antisera

Abstract

Summary and Conclusions: A method has been described for the determination of the precipitative strength of an antiserum, utilizing the combined methods of agglutination of collodion-particles coated with a purified protein, and the resuspension-agglutination technic. It is possible in this way to determine precipitative titers simply and accurately by serial dilution of the antiserum, as with other serologic procedures. Because of the simplicity of the collodion-agglutination method, relatively large numbers of antisera can be quickly and conveniently titrated and their precipitative strengths determined and compared with the skin-reactivity of the animals from which the serums were secured. The method is sharply specific, and is delicate enough to demonstrate the presence of precipitins in sera so weak that no visible precipitate occurs when they are mixed with varying dilutions of specific antigen. By this method, specific precipitins have been demonstrated in sera from patients hypersensitive to egg-protein, tuberculin and crystalline-insulin. There is reason to hope, therefore, that it may be of value for the quantitative study of the relationship of precipitins to various types of hypersensitive reactions.