The Precipitin Reaction of Antipneumococcus Sera

Abstract

The study of the precipitating reaction between antipneumococcus sera and the soluble specific substance derived from the three fixed types of Diplococcus pneumoniae promises a quantitative method for measuring the antibodies present in antipneumococcus sera. The relative simplicity in the chemical composition of one of the constituents, namely the soluble specific carbohydrate, paves the way for making this immunological phenomenon better understood.There is little doubt that the mutual compensation of electrical charges between two reacting colloids causes the phenomenon of precipitation (1, 2). So far colloidal chemistry offers an explanation for the mechanism of the reaction but not for the cause of its specificity toward that part of the colloidal serum constituents commonly known as antibodies. Avery, Heidelberger, and Goebel (3) demonstrated that the type specificity of the antigen is accounted for by distinct differences in chemical composition between the soluble specific substance of the three fixed types. The carbohydrates with their variability of configuration are apt to cause great physiological specificity, e.g. in the enzymatic hydrolysis of saccharides.On the other hand, the knowledge of the chemical nature or even of the concentration of the active specific principle of the other participant, the antibody, is so obscure that a differentiation of types from this angle seems futile at the present time.

The Precipitin Reaction of Antipneumococcus Sera

“…In the first paper of this series (1) it was stated that the precipitin index "offers a method for the standardization of pneumonia antibody." In a second paper (2) we concluded that "the ratio precipitin index/protective units in monovalent sera was found to lie between 2.8 and 4.8 for Type I and to be about ten times greater for Type III."…”