A Rapid Combined Slide Precipitation and Complement Fixation Test for Syphilis

Abstract

The reaction between syphilitic serum and antigen manifests itself either in the formation of a precipitate or in fixation of an added complement. The fixation process is a prolonged one, requiring one hour or more, while the precipitation occurs almost immediately. Since in the syphilitic sera the same principle is accepted to be responsible for both the fixation of complement and flocculation, the reason for such a difference in the course of both reactions may depend on the concentration of the ingredients. In the various modifications of the Wassermann test the syphilitic serum, antigen and complement are used in diluted form, while the newest precipitation tests (Kahn, Citochol, Kline, Rosenthal) employ undiluted serum and concentrated antigen. It occurred to us that it might be possible to obtain a rapid fixation of complement by using the ingredients in the same concentration as in the precipitation tests. At the same time such a procedure would permit the combination of flocculation and complement fixation in one test.

Keining, 1 Kafka, 2 Kahn, Landau and McDermott, 3 in an attempt to combine complement fixation and floceulation added complement to a mixture of serum and antigen after the formation of a precipitate had already taken place. They then allowed an incubation of 1/2 to 1 hour for the fixation of the complement as in the classical Wassermann test.

In our preliminary experiments we learned that the mixture of syphilitic serum and antigen was frequently unable to fix the complement if the latter was added at the end of precipitation. We, therefore, concluded that the syphilitic serum must first be mixed with the complement and only then receive the antigen. In many controls we found that the presence of this complement in a mixture of syphilitic serum and antigen, even in amounts exceeding those used in our test, in no way interfered with the precipitation.