ANTI-ENZYME IMMUNITY 361 



either of these enzymes plays any substantial part in the genesis of 

 fatal gas-gangrene. 



The findings of MacFarlane and MacLennan (1945) showed that 

 gangrenous muscle samples contain 173 per cent more extractable fat 

 than normal muscle. This may have a significant bearing on the fat 

 catabolism in gas-gangrene, Frazer, et at. (1945) studied the effect of 

 CI. welchii toxin on tissue and fluid substrates in vitro, in animals, and 

 in human subjects, with special reference to the effect of lecithinase 

 on structural lipids. Direct local effects on connective tissue, striated 

 muscle, adipose tissue, and peripheral nerve were described. The action 

 of the toxin on red blood cells, chylomicrons, and plasma lipoprotein 

 complexes was compared in guinea pig and man. Demyelination in the 

 central nervous system was demonstrable in vitro and in experimental 

 and clinical studies. Fat-embolism was produced experimentally by 

 intramuscular or intraperitoneal injection of CL welchii toxin, and has 

 been demonstrated in human postmortem material. The origin of the 

 fat in the animal experiments was considered to be the site of local 

 tissue destruction. 



Pertaining to the reasons for the failure of preventive measures with 

 the use of antitoxin the following observations are significant. Zamec- 

 nik and Lipmann (1947) found that the substrate lecithin interferes 

 with the combining reaction of CI. welchii a-toxin (lecithinase) and 

 a-antitoxin. If the lecithinase and lecithin are brought together first, 

 the antitoxin fails to inhibit the enzymatic reaction, but gradually 

 decelerates it. If the lecithinase is brought together with a mixture of 

 lecithin and antitoxin, it appears to combine in part with each, and 

 the enzymic process takes place at a reduced rate, which gradually 

 declines farther. If, on the other hand, the lecithinase is first brought 

 into contact with antitoxin, before lecithin is added, the enzymatic 

 reaction is completely inhibited. These facts show: (a) that both the 

 substrate and the specific antitoxin compete for the same active site of 

 the enzyme; (b) that the enzyme-substrate complex is dissociable; and 

 (c) that toxin-antitoxin combination is relatively non-dissociable. 



