The Standardization of the Hemolytic Index.

Abstract

During our studies of the effect of hemolytic amboceptors on different tissues the necessity arose for the creation of a standard for the comparison of the hemolytic index of different seras. Everyone who has worked on similar problems has no doubt encountered the disadvantages of the present system of plus symbols. Not only is it subject to the personal interpretation of the investigator, but the varying degree of the hemolytic index of a given serum will depend on the age of the serum and the temperature of preservation. Furthermore the following variants of the blood cells have to be taken into consideration: Condition of the animal at the time of taking the blood, methods of preventing coagulation, differential count of the different blood-elements, volume of the red blood-cells, time of centrifugation, temperature during centrifugation, and, the most important factor of all, the increased sensitivity of the red blood cells, which rapidly increases with the time of preservation.

In order to be independent of all these variants it was thought desirable to have a standard hemolytic chemical agent, the action of which might be compared with the hemolytic effect of a given amboceptor. For this purpose sapotoxin was prepared from Quillaja bark saponin (Merck, crude), following with minor variations the methods described by Kobert and Brandl. 1 Sapotoxin has the advantage of being more effective than saponin and the methods of purification guarantee a more uniform product than the different commercial saponins.

Two systems were prepared. The first one consisted, as ususal, of the hemolytic serum in varying amounts plus complement (guinea pig), plus 1 cc. of a 5% emulsion of red blood cells, which had been washed 3 times with a 0.85% NaCl solution.