152 ANTIGENS AND THE TECHNIC OF SERUM REACTIONS 



great detail and demonstrated by very careful and ingenious experi- 

 ments that the phenomena observed by Bordet were fundamentally 

 correct. They showed : 



1. That inactivated specific hemolytic serum (heated to 55 C.) 

 was absorbed by the homologous red blood cells, and that these " sen- 

 sitized" cells, separated from the serum after a few hours and washed 

 carefully, were readily hemolyzed when resuspended in salt solution 

 to which was added a small amount of fresh, unheated, normal guinea- 

 pig serum. 



2. The supernatant residual fluid from which the red blood cells 

 had removed all the immune body was incapable of causing hemolysis 

 of the homologous red blood cells when fresh normal serum was added 

 to it. The erythrocytes, in other words, quantitatively removed the 

 thermostabile "substance sensibilitrice" from solution. 



3. If normal sera were allowed to remain in contact with the same 

 red cells for an equal length of time, and these red cells were then 

 removed by centrifugalization and resuspended in salt solution con- 

 taining normal fresh serum, no hemolysis took place, leading to the 

 conclusion that the thermolabile substance (alexin of Bordet) is not 

 removed from solution by erythrocytes. Apparently alexin is not 

 bound or anchored directly to the red cells. 



4. Finally, it was shown that inactivated immune serum, red blood 

 cells and fresh normal serum could be maintained at C. without 

 apparent hemolysis. At 37 C. the same solution soon exhibited com- 

 plete hemolysis. Thus, at the lower temperature, the normal serum 

 failed to cause hemolysis. If the mixture maintained at C. were 

 centrifugalized, however, after some hours, and the red blood cells 

 washed thoroughly and resuspended in salt solution, hemolysis 

 promptly occurred when a small amount of normal serum was added 

 to the suspension, thus showing clearly that the inactivated immune 

 serum was bound or anchored by the red blood cells at C., even 

 though activation did not take place. 



Ehrlich substituted the term "amboceptor" for Bordet's term 

 "substance sensibilitrice" and complement for the term "alexin," 

 and conceived that the immune body amboceptor consisted essen- 

 tially of two combining or haptophore groups one the cytophilic 

 group, possessing a specific combining power for the specific cell 

 (bacterium or erythrocyte), the other, complementophilic group, 

 combining with the non-specific complement. According to this 

 theory the union of complement to specific cell takes place through the 



