HEMOLYSINS 77 



The conditions of interaction and neutralization of antigen and 

 antibody are not always as simple as in the case of toxins and anti- 

 toxins. They are more complicated with reference to other anti- 

 bodies, and it will be well to look into one important example of this 

 kind. 



Hemolysins. If we inject into the body of a guinea-pig at proper 

 intervals and in proper doses cholera spirilla the animal develops 

 an immune serum which has the property of dissolving cholera 

 spirilla. This property of the immune serum is due, as stated before, 

 to a particular kind of antibody known as lysins. If we inject into 

 a rabbit the red blood corpuscles of a sheep the former will develop 

 an immune serum which has the property of dissolving sheep's cor- 

 puscles. This property of the injected or sensitized rabbit's serum 

 is due to an antibody of the lysin type called a hemolysin. It consists, 

 as can easily be shown, of two bodies which can be separated and 

 studied separately. One of these two constituents which make up 

 the complete hemolysin is already found in the normal serum of 

 most animals; the other constituent antibody is only found in the 

 immune serum (the serum of the sensitized rabbit) or at least 

 found there only in large amount. The body found in normal 

 serum is called the complement, and the other the immune body or 

 amboceptor (why this latter name is used will be explained presently). 

 The complement is an antibody which is very easily destroyed and 

 cannot stand a temperature of 56 C. if applied to a serum containing 

 it for thirty minutes. Hence, the complement is said to be thermo- 

 labile. The amboceptor, on the other hand, can well stand heating 

 for thirty minutes at 56 C.; therefore, it is said to be thermostabile. 

 If an immune serum containing a hemolysin is heated for thirty 

 minutes at 56 C., destroying the complement, but not the amboceptor, 

 it is said to be inactivated, because it now cannot bring about hemo- 

 lysis. If, however, some normal non-heated serum which, as stated, 

 contains the complement is added to an inactivated serum the im- 

 mune serum is again reactivated because it can once more bring 

 about hemolysis (solution of the red blood corpuscles). This method 

 of inactivating the immune serum and using it in connection with 

 reactivating normal serum makes it possible to study the ambo- 

 ceptor and the complement separately and to learn how they act, how 

 they anchor themselves to the red blood corpuscles, and how, by so 

 doing, they bring about hemolysis. The process by which this 

 occurs is the following: The amboceptor has one group, or side-chain, 

 which fastens itself to a receptor of the red blood corpuscle, and a 

 second group, or side-chain, by which it attracts and anchors to itself 

 the complement. Only after the amboceptor has become united to 

 both the complement and the red blood corpuscle can the solution 

 of the latter (hemolysis) take place. The union of (1) red blood 

 corpuscle, (2) amboceptor, and (3) complement is called a complete 

 hemolytic system or chain. This explains why the immune body in 



