6 QUATERCENTENARY STUDIES IN PATHOLOGY 



Savtchenko and Berdnikoff (2), as well as Donath and Landsteiner (3) 

 and Domeny (4), all controverted the view of Metchnikoff that the 

 macrophages possess a thermolabile enzyme or cytase, which, passing 

 into the bFood, affords to this its haemolytic power. Metchnikoff, however, 

 received support from Levaditi (5), who found that such extracts, when 

 fresh, possessed this thermolabile substance, but when old, lost it, and it 

 therefore appeared probable to Metchnikoff that the macrophages 

 contained a thermolabile enzyme which causes dissolution (autolysis) 

 of the cells of such extracts as contain macrophages, and that in the 

 course of autolysis, among the newly formed substances, arises a number 

 of haemolytic substances of a thermolabile nature. 



Levaditi further supported Metchnikoff by showing that fresh extracts 

 of lymph glands contained a macrocytase, and that by means of it 

 one could reactivate sera which had been rendered inactive by heat. 



The position held by Metchnikoff was the following. He considered 

 that the macrophages of the lymph glands and other macrophage-forming 

 organs greedily devoured various cellular elements, amongst which were 

 red blood cells. They proceeded to digest these ingested cells, in which 

 process the thermolabile enzymes or cytases possessed by the macro- 

 phages played a prominent part. To this thermolabile enzyme or cytase 

 he attributed also the power of causing extra-cellular haemolysis of 

 red blood cells, and held that it gained access to the blood frqm the 

 macrophages, and thus lent to the serum its haemolytic power in cases in 

 which it was possessed of such. 



These views were destined to be subjected to considerable discussion 

 and change. Bordet found that in animals into which blood had 

 been repeatedly injected, the haemolytic action of the macrophage 

 extracts was not increased, while that of the blood serum was 

 much augmented if already present, and produced de novo, if not 

 originally there. He demonstrated, too, that instead of a single 

 cytase there were two substances concerned in haemolysis, one 

 of which, alexine, was present to the same extent in normal as 

 in immune serum. This substance was destroyed at temperatures 

 between 56° C and 60" C. In addition to this complement, however, he 

 showed that in haemolytic sera there was another substance, which he 

 termed the substance sensibilisatrice, from the idea that it made the red 

 blood cells sensitive to the action of the alexine. Bordet showed that it 



(306) 



