COMPLEMENT 165 



sis of the specific foreign cell, is something normally present in the 

 serum of every animal, and which is capable of disintegrating a foreign 

 cell or bacterium, provided it can have access to the cell or bacte- 

 rium through an intermediary ambpceptor (hence the amboceptor is 

 sometimes called an intermediary body). This something is called 

 the complement. It is by some called alexine, by others cytase 

 (Metchnikoff). ' ^_ _^^^^" 



The complement cannot act upon and destroy an invading bacterium or cell unless 

 the amboceptor is present to make the necessary connection. The complement is 

 destroyed by a temperature of s6C., so that, if we heat the serum from an immune 

 animal to s6C., the complement it naturally contains is destroyed, and the ambo- 

 ceptor it contains, which is not injured by such a temperature, is incapable of de- 

 stroying bacteria or cells, unless we replace the complement which has been destroyed 

 by fresh complement. This is done experimentally by adding the serum of a non- 

 immunized animal which contains the complement, but no specifier immune body 

 (amboceptor), to the heated serum. This is termed "activating," and a serum so 

 treated is said to be "activated." When an immune serum has been heated to 56C., 

 it is said to have been "inactivated." 



Antirnicrobic sera are not as efficient in treatment as antitoxic ones. 

 It might be that if we could use homologous sera for treating man instead 

 of the usual heterologous ones from the horse better results might 

 obtain. 



It would appear that a more hopeful outlook will obtain by combining serum 

 therapy with chemo-therapy, thus a combination of antipneumococcic serum with 

 sodium oleate seems capable of producing curative results which neither alone can 

 bring about. 



Again, a combination of vaccination (active immunization) with the injection of 

 the antimicrobic serum (passive immunization) has been thought by some to be of 

 value. 



When we allow a mixture of bacteria or cells to remain in contact 

 with their specific imrrmne^serum which has been inactivated, the ambo- 

 ceptors attach themselves to the bacteria or cells, so tnat now, upon 

 adding normal serum (complement), these bacteria or cells are so 

 prepared or mordanted that the complement can disintegrate them. 

 This experiment of attaching amboceptors to cells is termed sensitizing 

 and cells so treated are said to be sensitized. 



METHODS FOR OBTAINING IMMUNE SERA 



While a convalescent from a disease may be utilized to obtain an 

 antitoxic, agglutinating, opsonic, or bacteriolytic serum against the 



