Varying Hemolytic and Constant Combining Capacity of Streptolysins; Influence on Testing for Antistreptolysins

Certain properties of streptolysin in respect of hemolytic power and capacity for combining with antistreptolysins have been determined. The hemolytic strength may vary markedly, while under suitable conditions the combining power is constant. This stability of combining capacity makes it possible to prepare a large amount of streptolysin, standardize it against sera of known antistreptolysin strength, and use it as a reagent over a considerable period for testing the antistreptolysin content of unknown sera. A modified technique for making these tests is described.