Chemospecific Flocculation of Sterols by Anti-Sterol-Sera

Abstract

Some years ago, one of us reported experiments concerning the antigenic qualities of cholesterol and derivatives of cholesterol, using the method of complement-fixation. 1 , 2 Flocculation tests, which were not published, confirmed the results with complement-fixation. In the meantime, Hahn and Hazado 3 reported experiments on a flocculation of cholesterol by cholesterol antisera. Since the demonstration of a specific and sensitive flocculation of cholesterol by the serum of animals injected with cholesterol (and a protein “schlepper”) furnishes a new and valuable argument for the haptenic quality of sterols, our own data are now given.

The great sensitivity of sterol sols toward salts may be obviated by adding 2 volumes of water to the serum-dilutions. The specific flocculation of sterol sols (prepared according to Keeser 4 ) is very slow under such conditions, but is maximal in 24 hours at room temperature.

Table I gives an example of such an experiment.

We were able to produce flocculations with cholesterol, di-hydro-cholesterol and oxy-cholesterol (Lifschütz) and the corresponding antisera. Data on the preparations used and the method of immunization are given in the papers of Weil and Besser. The qualitative and quantitative relations of specificity were the same as reported for the complement-fixation test, that is, there is some cross-reaction between cholesterol, di-hydrocholesterol, and oxycholesterol (Lifschütz), but the specific antigen showed always a much stronger flocculation and a higher titer than the others. None of our sera reacted with cholesterol dibromide, cholesterol acetate, cholesterol palmitate, or cholesterol oxide (Westfalen), nor was there any reaction of these sera with alcoholic extracts of beef heart. Sera of normal rabbits, including those of our rabbits before immunization, gave no reaction with any of these substances.