374 HEMOLYSINS 



The hemolysins have no therapeutic application or value. They 

 have their chief value in diagnostic reactions and in the study of cyto- 

 lytic phenomena in general. 



Quantitative Relationship between Hemolytic Amboceptor and 

 Complement. From a practical as well as a theoretic standpoint an 

 important property of amboceptor and of complement is the quanti- 

 tative relationship that each bears to the other. This is especially im- 

 portant in hemolytic reactions, where an excess of either may compen- 

 sate for a decrease of the other and yield fallacious results. If a certain 

 amount of guinea-pig's complement is necessary to lyse 1 c.c. of a 2.5 

 per cent, suspension of sheep's cells, along with hemolytic amboceptor, 

 then double this amount of complement will be required to lyse 2 c.c. 

 of the same blood, and so on. If a constant quantity of corpuscles and 

 hemolysin are added to a series of test-tubes, and increasing amounts of 

 complement after incubating the mixtures for an hour the smallest 

 amount of complement that produces complete hemolysis is called a 

 umtj and in this manner the strength or activity of a serum complement 

 is measured or titrated. In a similar manner the hemolytic activity of a 

 serum or its measure of hemolysin may be determined by placing in a 

 series of tubes, as previously directed, a definite and equal amount of 

 corpuscle suspension, and to each tube is then added an amount, also 

 definite and equal, of a normal serum as complement, which is known 

 to be incapable of causing hemolysis. There are next added decreasing 

 and graduated amounts of the immune serum whose native complement 

 has been destroyed by inactivation. After incubating the mixtures for 

 an hour, the smallest amount of inactivated immune serum that will just 

 produce complete hemolysis is known as the amboceptor unit of the serum. 

 In other words, there are three substances concerned in serum hemolysis: 

 the amboceptor, the corpuscles, and the complement. By taking two 

 of these as constants, e. g., the corpuscles and the complement, the unit 

 of amboceptor may be determined; or by taking the corpuscles and 

 Amboceptor as constants the unit of complement may be determined. 

 Since the corpuscles and amboceptor are most stable, these may be 

 used as constants, and the unit of complement determined under these 

 conditions as psejjminary to complement-fixation reactions. 



^4-f is 'important to bear in mind, in this connection, that the titer of 

 an immune hemolytic serum will vary with the complement used. For 

 example, an antisheep amboceptor is much more active when guinea-pig 

 serum is used as complement than it is when tested with the same quan- 

 tity of rabbit serum as complement. 



