Measurement of Reagin in Non-Syphilitic Sera. ∗

Abstract

The reporting of serological tests for syphilis as positive or negative implies a qualitative difference between the bloods of syphilitic and non-syphilitic individuals. This concept assumes the presence in the serum of syphilitic patients of a substance designated as “reagin”, which is lacking in patients without syphilis. In syphilitic patients, treated or untreated, it is highly probable that small amounts of reagin persist even though the serum is negative to the usual tests. As yet there is no evidence that reagin may not also be present in non-syphilitic sera.

If reagin is to be demonstrated in non-syphilitic sera, it is necessary to use a test so sensitive as to be invariably positive, to concentrate the serum, or to increase the reagin content to a point where it can be detected by the usual tests. We have chosen the last method, adapted from the work of Schreus and Foerster 1 who studied the Wassermann reaction in syphilitic patients treated to seronegativity. By adding to the sera of these patients subthreshold amounts of positive sera, these workers were able to obtain positive reactions. In place of the Wassermann we have substituted the Kline test because of its simplicity.

Suspensions are prepared from standard Kline antigen in the usual way. A stock reagin solution is prepared from positive serum after inactivation for 15 minutes at 56°C. Double precipitation is carried out in half saturated ammonium sulphate as described by Schreus and Foerster. The second precipitate is dissolved in a minimal amount of normal saline. The reagin content of this stock reagin solution decreases less rapidly than that of untreated serum according to these workers. This solution is now diluted 10, 20, 30, 40, and 50 times with saline and the Kline test 2 is performed with these dilutions to determine the approximate titre.