198 



THE ANTIGEN-ANTIBODY REACTIONS 



or precipitation, Ehrlich postulated the existence of another grouping in the 

 receptor, which determined the particular change in the condition of the antigen 

 after the antibody was anchored by its haptophore group. This second, active, 

 group was named by Ehrlich the ergophore group. In certain cases, which we 

 discuss more fully below, it became necessary to postulate the existence of receptors 

 which, while themselves inactive, served to unite an antigen to a second active 

 substance, the complement or alexine to which we have referred above. To meet 

 c ■ this case Ehrlich postulated the 



existence of receptors with two 

 haptophore groups, one of which 

 became attached to the antigen to 

 be acted upon, and one to the 

 complement which was the acting 

 substance. Both these groups 

 were to be regarded as strictly 

 specific in their chemical affini- 

 ties. The one which combined 

 with the cell or other antigen to 

 be acted upon was known as the 

 cytophilic group, the one which 

 combined with the complement 

 was referred to as the comple- 

 mentophilic group. Ehrlich named 

 this type of receptor an ambocep- 

 tor, because both groups were 

 supposed to be of the haptophore 

 type. He also referred these 

 three types of receptors to three 

 orders, the first having a single 

 haptophore group, the second one 

 haptophore and one ergophore 

 group, and the third two hapto- 

 phore groups. 



Fig. 31 gives a diagrammatic 

 representation of Ehrlich 's general 



Fig. 31. 

 CI. Cell. 



1. Receptor of 1st order with its haptophore group h. 



2. Receptor of 2nd order with its haptophore group 



h' and its ergophore group e. 



3. Receptor of 3rd order with its two haptophore 



groups, h" the cytophilic group, and h'" the 

 complementophilic group. 



a', a". Various antigens, each with its hapto- 

 phore group h ; A has in addition an ergo- 

 phore, or toxophore group (. 



Complement, with its haptophore group h, and 

 its ergophore group c'. 



A, 



conception. 

 Ehrlich regarded these receptors as definite chemical entities which entered 

 into firm union with antigens, or with complement, by linkage of the corresponding 

 haptophore groups. When it was found that such antigens as the toxins could 

 be so treated as to lose their toxicity without losing their power of combining with 

 antitoxin, he assumed that the toxophore group had been altered or destroyed, 

 while the haptophore group remained intact. Similarly he postulated the existence 

 of a modified complement, in which an intact haptophore group was associated 

 with an ergophore group which had lost its functioning power. It will be realized 

 that such a theory lent itself readily to schematic representation of the various 

 reacting substances, and their assumed modifications, and that there was a natural 

 tendency to elaborate the assumed structure, and vary the functional activity of 

 the various groups, to account for new phenomena not readily explicable by the 

 unmodified hypothesis. This is in fact what happened. 



