546 . Dr. R. D. Keith. Relationship between [Feb. 15, 



suspension of washed guinea-pig red cells. When heated at 55° C, however, 

 such a serum, failed to induce phagocytosis of the red cells after 15 minutes 

 at 37° C, equal parts of the serum, of the suspension of red cells and of 

 washed human leucocytes being employed. 



All these facts then tend to show that the haemolytic amboceptor may be 

 present m a very considerable amount in a serum without giving to the 

 latter the power of inducing phagocytosis of the appropriate red blood 

 cells. 



Conclusions. — The conclusion naturally come to is that the phagocytosis of 

 red blood cells does not depend on the presence of the hemolytic amboceptor, 

 since : — 



1. The substance which induces phagocytosis is partially destroyed by 

 heat, while the hemolytic amboceptor is entirely thermostable. 



2. The hemolytic amboceptor may be present in considerable amount 

 in a hemolytic serum without inducing, phagocytosis, notwithstanding 

 prolonged contact of the amboceptor with the red blood cells. This is 

 contrary to the opinion of Savtchenko.* 



Deanj has suggested that phagocytosis may be caused by a complement 

 acting through an amboceptor, and that the partial destruction, of the 

 property in the serum inducing phagocytosis, . by heat may be due to the 

 destruction of the complement, while the amboceptor, even in the absence of 

 the complement, may still be capable of inducing phagocytosis. This theory, 

 while it is difficult to disprove directly owing to the complement being 

 destroyed at the same temperature as the thermolabile part of the substance 

 inducing phagocytosis, seems to be an improbable one for the following 

 reasons : — ' , 



(1) That it is not an action analogous to that of other amboceptors, 

 e.g., that concerned in haemolysis. If one destroy the complement of a 

 httmolytic serum by heat, no haemolysis takes place, notwithstanding the 

 presence of the amboceptor in large amount. 



(2) As has been shown above, the haemolytic amboceptor may be present in 

 large amount in a diluted serum, without that serum having the power of 

 inducing phagocytosis even when Dean's method of testing is employed. \ 



(3) , In the dilution experiments recorded above it was shown that one 

 may dilute the complement to such an extent as to abolish haemolysis, and yet 

 such a serum has a greater " opsonic " power in these dilutions than has the 

 same serum when heated and employed in corresponding dilutions. 



If the amboceptor act in the way Dean suggests, it must be supposed to 



* Loc. cit., p. 118. 

 i, Loc. cit. 



