606 COLLECTED STUDIES IN IMMUNITY. 



Since experience has shown that normal sera so frequently 

 exert anticomplementary powers, we are compelled to assume 

 that the normal amboceptors, of which, as is well known, large 

 numbers circulate in the blood, generally possess a high affinity to the 

 complement. Thanks to this high affinity they are able to deflect 

 the complement from the amboceptor concerned in the reaction. 

 Naturally, the question whether in a given case the amboceptor 

 is to act as such or as anticomplement, will depend in general on 

 whether it fits the given species of cell or not. In any event, the 

 anticomplementary action as thus conceived corresponds entirely 

 to Neisser and Wechsberg's phenomenon of deflection of comple- 

 ment by an excess of amboceptor, 



Returning now to the problem under discussion, we find that 

 this finds a ready explanation along the lines indicated. This 

 will be clear on studying the schematic figure appended. 



FIG. 1. FIG. 2. 



I A = immune amboceptor. NA = normal amboceptor. AC = normal ambocep- 

 tors functioning as anticomplements. C = complement. 



In Fig. 1 is represented the action of native rabbit serum on 

 the ha3molysis of sensitized sheep blood-cells by guinea-pig com- 

 plement. The sheep blood-cells are loaded with the immune ambo- 

 ceptor (I A). The normal amboceptor of rabbit serum fitting to 

 sheep blood-cells (NA) has likewise been anchored by the cell, and 

 has laid hold of the complement. 1 



In Fig. 2 the normal rabbit serum, through digestion with sheep 

 blood-cells, has lost its amboceptor for these cells. Under these 



1 The higher affinity of the normal amboceptors will be still further increased 

 in favor of those bound to the cell, for it is well known that in combining with 

 the cell the complementophile group acquires an increased affinity. 



