STUDIES ON ANTIAMBOCEPTORS. 661 



ceivable that even under these circumstances, the antiamboceptor 

 is always bound, but that in many cases this union can still be 

 dissolved by the complement owing to the absence of the deflecting 

 precipitate. If we accept this secondary participation of the pre- 

 cipitate in the antiamboceptor action, it is easy to understand the 

 apparent failure of the antiamboceptor to be bound to the sensitized 

 blood-cells. Some explanation for this lack of combination is 

 certainly desirable. One would naturally expect the antiambo- 

 ceptor to act more powerfully on the sensitized blood-cells, for in 

 blood-cells laden with amboceptor the free, normal amboceptors of 

 the immune serum are absent. These free amboceptors come into 

 action when the antiamboceptor acts directly on the entire immune 

 serum, and they can thus lower the action of the antiamboceptor on 

 the specific amboceptor. As a matter of fact, we have encountered 

 instances in which the antiserum acted just as strongly on the 

 sensitized cell as on the native immune serum. In other cases, 

 however, the antiserum, when employed in accordance with the 

 usual technique (sensitized blood + antiserum one hour at 37 

 centrifuging addition of complement two hours at 37), exerted 

 no action whatever. This was the case with the antiserum whose 

 properties we have discussed in this paper. 



These considerations led us to see if we could make the action 

 of the antiserum on the sensitized cell visible. To do this we felt 

 that two things in particular had to be regarded. In the first place, 

 it seemed advisible to leave the antiserum in contact with the blood- 

 cells laden with amboceptor as long as possible, in order to effect 

 the maximum amount of binding with the antiamboceptor. This 

 would make it more difficult for the complement subsequently added 

 to dislodge the antiamboceptor. In the second place, it seemed 

 probable that the complement only gradually displaced the anti- 

 amboceptor, and that examinations made at intervals would reveal 

 a phase in which an antiamboceptor action can be observed. 



We arranged our experiment as follows: 



an interfering action produced by two antibodies in the antiserum, bodies 

 having the type of antiamboceptors. So far as the details are concerned we 

 must refer to the original paper of Ehrlich and Sachs. Here we would only 

 remark that the interpretation given at that time is applicable also to those 

 cases in which the antiamboceptor is without effect when sensitized blood- 

 cells freed from normal serum constituents are employed. 



