604 



COLLECTED STUDIES IN IMMUNITY. 



ceptors acting on sheep blood-cells. If one allows the normal 

 amboceptors to participate in the reaction by themselves, it will be 

 found that the antilytic effect is not produced. 



The demonstration is made as follows: An inhibiting serum, 

 prepared by treating rabbit serum with sheep blood-cells, is mixed 

 with complement (0.1 cc. guinea-pig serum) and allowed to act 

 on sheep blood-cells which have been sensitized in one case with 

 immune serum, in another case with this and normal rabbit serum. 

 The result is shown in the following table. 



In Column I the reagent consisted always of 1 cc. 5% sheep 

 blood sensitized with 0.002 cc. immune serum obtained by im- 

 munizing a rabbit with ox blood-cells. 



In Column II, the sheep blood was treated in exactly the same 

 manner, and then digested with 0.5 cc. normal rabbit serum, where- 

 upon the blood was freed from serum by centrifugalization. 



TABLE II. 



It will be seen from the table, that through the coaction of 

 the normal amboceptors of rabbit serum, the antilytic action dis- 

 appears, and this at once explains why the inhibiting function 

 should be absent in native serum. The inhibiting antibodies are 

 really present in native rabbit serum from the outset, but they 

 are hidden by the simultaneous action of the normal amboceptors. 

 The experiment further shows that the digestion of serum with 

 blood-cells does not bring about, for example, a tearing off of receptors 

 through the agency of the normal amboceptors. (Such a combina- 

 tion in the serum fluid, moreover, would really act like an anti- 

 complement). Column II shows that the normal amboceptors are 

 really bound by the blood-cells. From the behavior of the various 



