CYTOLYSINS 137 



were of the opinion that such anti-amboceptors represented an excess 

 of cell receptors formed during the course of immunization and were 

 thus free in the serum to combine with the cytophilic group of the 

 amboceptor. Bordet found, however, that it was not necessary to use 

 a hemolytic immune serum as an antigen and demonstrated an anti- 

 amboceptor by injecting normal rabbit serum into guinea-pigs. The 

 anti-serum formed in the guinea-pig not only neutralized hemolytic 

 amboceptor of rabbit serum but other amboceptors of rabbit serum as 

 well, and therefore it could not be regarded as combining with such 

 a specific receptor as the cytophilic group of the amboceptor. This 

 work was confirmed by several investigators, including Ehrlich and 

 Sachs, who agreed with Bordet that the anti-amboceptor does not com- 

 bine with the cytophilic group but offered the new assumption that the 

 combination is with the complementophilic group. Muir and 

 his co-workers have studied anti-amboceptors extensively and find 

 no good ground for accepting the later interpretation of Ehrlich 

 and Morgenroth. 



Muir offers an experiment as follows to illustrate the simple action 

 of anti-amboceptor. Two tubes are marked A and B. Into each are 

 placed one unit of cell suspension and three units hemolytic amboceptor 

 (contained in rabbit serum), the mixture incubated and then washed 

 and resuspended. To tube A is added 0.3 c.c. anti-amboceptor (pre- 

 pared by injecting rabbit serum into guinea-pig), and to tube B is 

 added 0.3 c.c. normal inactivated guinea-pig serum. The mixtures are 

 again incubated and washed; to each tube is added one unit comple- 

 ment and the tubes are again incubated. Hemolysis is complete in 

 tube B but is absent or much inhibited in tube A, thus demonstrating 

 the inhibiting effect of the anti-amboceptor. Such an anti-amboceptor 

 as is here illustrated will operate only against amboceptors contained 

 in rabbit serum. Similar amboceptors contained in goat serum would 

 not be affected by the anti-amboceptor prepared by injecting rabbit 

 serum into guinea-pigs. If in the preceding experiment the supernatant 

 fluid were examined after the first incubation it would be found that 

 the amboceptor had been absorbed; a fact also illustrated by the 

 hemolysis in tube B. Even were anti-amboceptor and amboceptor 

 mixed and then added to cells the amboceptor would not be prevented 

 from absorption. If the supernatant fluid were taken after the last 

 incubation complement would be found free in tube A but not in the 

 full original amount, as can be shown by careful titration. The anti- 

 amboceptor keeps a certain amount but not all the complement from 

 being utilized. The converse, however, cannot be demonstrated, that 

 is to say, complement cannot be shown to inhibit in any way the union 

 of amboceptor and anti-amboceptor. Intricate experiments demon- 

 strate, however, that the union of amboceptor and anti-amboceptor is 

 loose and a certain amount of dissociation may occur upon the addi- 

 tion of a normal serum homologous with the serum which contains 

 the amboceptor. 



Anti-complements. As has been indicated above, it is improbable 



