Dilution of antigen for Wassermann test

Abstract

In the previous communication, the author described a method for preparing antigen for the Kahn Precipitation Test and showed (Procedure II) that the sediment formed on mixing and centrifuging equal quantities of antigen and salt solution may be redissolved in salt solution and employed in the above test for syphilis. The question came up whether the same sediment taken up in salt solution may not be used as an antigen in the Wassermann test and the following experiments were carried out accordingly.

A cholesterinized extract regularly used in the Wasserman test in a dilution of 1: 70 with salt solution was employed. One c.c. of this extract was measured into a small tube and one c.c. of salt solution added to it. This was mixed and centrifuged, after which the supernatant fluid was poured off and the sediment suspended in 70 c.c. salt solution. This mixture was tested for anti-complementary, hæmolytic and antigenic properties side by side with a suspension prepared by slowly adding 70 c.c. saline to 1 c.c. antigen.

It was found that the suspension prepared from the sediment which resulted from mixing equal amounts of salt solution and antigen was considerably less anticomplementary as well as less hzmolytic than the suspension prepared by adding salt solution to antigen in the regular manner. It was further found that the antigenic properties of the suspensions resulting from either of the two modes of mixing with salt solution was about the same. Similar experiments gave the same results.

Clinical studies may ultimately establish that salt solution suspensions of the lipoid sediment possess high specificity and that the occasional non-specific Wassermann reaction given by cholesterinized antigens may be avoided by employing resuspended antigen-salt solution sediments.