COMPLEMENTS 349 



cytophile group. In other words, the theoretic structure is similar to 

 that of a toxin, although the function and action of the two are quite 

 different. 



By heating a complement serum to 55 C. for half an hour the cyto- 

 phile portion is destroyed, and the serum is now said to be inactivated, 

 as the complement is no longer active. If the complement serum is 

 allowed to stand at ordinary room temperature for forty-eight hours or 

 longer, the same change will take place. The cytophilic or active por- 

 tion of the complement is, therefore, quite unstable. When this portion 

 is altered or lost, the substance is called complementoid, and this is anal- 

 ogous to toxoids and agglutinoids. 



Since complementoids have their haptophore groups intact, they will 

 unite with amboceptors and to some extent prevent lysis by blocking the 

 active complement, just as toxoids unite with antitoxin and agglutin- 

 oids with their antigens. 



Anticomplements may be obtained by immunizing suitable animals 

 with serums that contain complement or complementoid. When an 

 inactivated anticomplement serum is mixed with the homologous com- 

 plement, the haptophores of the latter are bound by means of the 

 haptophbres of the anticomplements. A proof of this union lies in the 

 fact that a complement serum that has been treated with its specific 

 anticomplement is no longer able to activate an appropriate amboceptor. 



According to Gay, the production of anticomplements is only ap- 

 parent; he explains the loss of complement activity when a fresh serum 

 and its antiserum are mixed as due to the absorption of complement in 

 the precipitate which forms, although the latter may be invisible. 



Anticomplements may be of practical importance owing to the forma- 

 tion of auto-anticomplements. The complements must exercise an im- 

 portant function, not only in the destruction of bacteria, but also in the 

 digestion and solution of all kinds of foreign albuminous bodies that 

 enter the organism. As was shown by Wassermann, anticomplements 

 may so bind up their complements as to render then* host much less 

 resistant to certain infectious diseases. The spontaneous development 

 of auto-anticomplement in an animal has never been demonstrated, as 

 there are no receptors in an organism of the complements of the same 

 organism. The injection of the serum of another animal containing 

 complements that are almost identical may, however, lead to the forma- 

 tion of an auto-anticomplement in the serum of the immunized animal. 



The extreme lability or sensitivity of complements to heat, exposure, 

 adds, alkalis, etc., is their most prominent general characteristic. An 



