SERUM ENZYMES 529 



of pneumonia, in which condition Falls 15 has shown a sudden dimi- 

 nution of this enzyme at the time of crisis, and the same author has 

 made analogous observations in the fluctuation of serum protease in 

 malaria, typhoid fever, and some other diseases. 



The lipolytic activity of the serum has been found increased in 

 syphilis, in diseases involving liver function, such as chloroform 

 poisoning, and in a number of other conditions. In syphilis, indeed, 

 the increased lipase contents have been held responsible for the Was- 

 sermann reaction by a number of writers. They believed that the 

 lipolytic ferment acting upon the lipoid antigen produced fatty acid 

 which by increasing the H-ion contents rendered the complement 

 inactive. This to a certain extent was strengthened by the knowledge 

 that in the Wassermann reaction the end-piece of complement re- 

 mained free. However, we ourselves in hitherto unpublished experi- 

 ments have been able to convince ourselves that there is no relation- 

 ship between lipase contents and Wassermann positiveness. 



Activity of intravascular enzymes of any kind may perhaps be 

 going on constantly in the normal course of life as a part of general 

 body metabolism; yet it is probable that any great extent, especially 

 of proteolytic action, would be incompatible with health or even 

 life. The work of Vaughan, of Friedberger, and others has shown 

 us that in the course of proteolysis toxic cleavage products, probably 

 of the albumose variety, are liberated. This we have seen has been 

 made the basis of some theories of anaphylaxis, and the "split prod- 

 ucts" of Vaughan, the "anaphylatoxin" of Friedberger, the "proteo- 

 toxins," as we ourselves have chosen to call them, and the "sero- 

 toxins" of Jobling and Petersen, all are probably the results of such 

 proteolysis. Indeed, as we have seen, the incubation of almost any 

 tissue substrate with fresh serum will result in this proteolytic 

 change and even in the formation of toxic substances. It was at first 

 thought that the toxic split products were derived from the substrate, 

 but we have seen in another chapter that the mechanism is probably 

 one in which antiferments are removed by the substrate, and the 

 serum-protease is liberated to act upon the serum protein itself. 

 This was undoubtedly the case in such instances as those in which 

 anaphylatoxin was obtained by digestion of serum with kaolin, 

 barium sulphate, tubercle bacilli, etc. 'Now it appears that the 

 injection of almost any substance, and especially of bacterial pro- 

 teins, produces a sharp rise of enzymes in the blood. This seems to 

 be true not only of proteolytic enzymes but of lipolytic and amylolytic 

 ferments as well. Ferments so stimulated are entirely non-specific. 

 This greater serum activity after protein injection may be due both 

 to a direct increase of production and a simultaneous diminution of 

 antiferments, by means of which activity hitherto inhibited is al- 

 lowed to run riot. The result may be in some respects beneficial 

 15 Falls. Journ. of Inf. Dis., Vol. 16, p. 466. 



