The effect of oxidation on Wassermann antigen

Abstract

In 1914 the authors had occasion to prepare some lecithin by MacLean's method (Journal of Pathology and Bacteriology, 18, p. 490). The method (an elaborate one) consists essentially of numerous precipitations out of ether and water, by means of acetone, of the alcoholic extracts of dried beef heart. The purified precipitate is finally dried in vacuo over sulphuric acid. Throughout the work air is excluded so far as possible.

In the present work from 6 1/2 kilos of lean pressed beef heart, about 8 grams of purified lecithin were obtained. The lecithin had a yellowish white waxy appearance and upon analysis was found to contain 4.06 per cent. phosphorus and 1.93 per cent. nitrogen. The nitrogen and phosphorus are in the ratio of one to one. It had an iodine number of seventy. Throughout the procedure every precaution was taken to exclude air by replacement with CO₂ so as to prevent oxidation as far as possible. Some of the lecithin was put in tubes in vacuo, and some in carbon dioxide gas.

The lecithin separated in this way is not true lecithin, but a mixture of true lecithin and kephalin. It possesses however all the properties of the substance generally alluded to as lecithin.

The samples of lecithin put up in tubes have been tested in the Wassermann reaction at various times during the last four years. It has been found that the antigenic property of those tubes which remained perfectly sealed was preserved and remained of practically the same titer as it was at the beginning. On the other hand, a considerable number of the tubes developed small cracks which admitted some air.‘ The dried antigen in these tubes changed in appearance, becoming very dark and confluent.