AMBOCEPTORS 269 



Therefore, there is something in heated immune serum neces- 

 sary for cell dissolving and something different in diluted 

 normal serum which is necessary. This latter something is 

 present in unheated immune serum also and is destroyed 

 by heat. Experiment has shown that it is the substance 

 present in all serum both normal and immune that is the 

 true dissolving body, while the immune substance serves to 

 unite this body to the cell to be destroyed, i. e., to the anti- 

 gen. Since the immune body has therefore two uniting 

 groups, one for the dissolving substance and one for the cell 

 to be dissolved, Ehrlich calls it the "amboceptor." He also 

 uses the word "complement'' to denote the dissolving sub- 

 stance, giving the idea that it completes the action of dis- 

 solving after it has been united to the cell by the amboceptor, 

 thus replacing Buchner's older term "alexin" for the same 

 dissolving body. 



AMBOCEPTORS. 



The theory of formation of amboceptors is similar to that 

 for the formation of the other types of antibodies. The 

 cell introduced contains some substance which acts as a 

 chemical stimulus to some of the body cells provided with 

 proper receptors so that more of these special receptors are 

 produced, and eventually in excess so that they become free 

 in the blood and constitute the free amboceptors. It will 

 be noticed that these free receptors differ from either of the 

 two kinds already described in that they have two uniting 

 groups, one for the antigen (cell introduced) named cytophil- 

 haptopliore, the other for the complement, complementophil 

 haptophore. Hence amboceptors are spoken of as receptors 

 or haptins of the third order. They have no other function than 

 that of this double combining power. The action which re- 

 sults is due to the third body— the complement. It will be 

 readily seen that complement must possess at least two groups 

 a combining or haptophore group which unites with the ambo- 

 ceptor, and an active group which is usually called the 

 zymophore or toxophore group. Complements thus resemble 

 either toxins, where the specific cell (antigen) is injured or 

 killed, or enzymes, in case the cell is likewise dissolved. 



