PROPERTIES OF COMPLEMENTS 39 



ON THE COMBINING PROPERTIES OF 



COMPLEMENTS 



The combining properties of serum-complement have been 

 studied in two chief relationships. In the first place, its 

 combination with red corpuscles or bacteria, through the 

 medium of the appropriate immune-body, has been investi- 

 gated to a certain extent, and facts of considerable impor- 

 tance have been obtained. Taking the case of haemolytic 

 sera, we may for the present put aside the question whether 

 the immune-body acts as a link (amboceptor) between the 

 molecule of the red corpuscle and complement (Ehrlich's 

 view), or whether complement enters into direct combina- 

 tion with the molecules of the red corpuscles through the 

 influence of the immune-body. If we represent the combining 

 molecules or receptors of the red corpuscles by R, and the 

 immune-body by IB, it is sufficient for our present purpose to 

 recognize that C (complement) combines with R + IB. In 

 the second place, the action of a supposed anti-complement on 

 complement has been studied. It was found that when 

 the serum of an animal of species A was injected into one 

 of species B, the serum of the latter acquired the property 

 of inhibiting the action of the complement of the former, 

 and Erhlich and Morgenroth 1 showed that this occurred by 

 the haptophore group of complement becoming filled up, so 

 that the complement could no longer combine with the 

 sensitized corpuscles and produce lysis. According to this 

 view, then, there was developed an anti-C, which neutralized 

 C. As the anti-complement action appeared even wheu the 

 serum injected had been heated at 55 C., Ehrlich supposed 

 that only the zymotoxic group of complement was destroyed 

 by heat, the haptophore group remaining ; in other words, 

 that complement is converted into complementoid on heat- 

 ing, and that the latter also has the property of giving rise 

 1 Ehrlich and Morgenroth, Berlin. Klin. Woch., 1900, No. 31. 



