354 IMMUNO-CATALYSIS 



by the toxins on the oxidation of lactate or malate by this enzyme 

 preparation was observed. The anaerobic reduction of methylene blue 

 in the systems containing minced intestine or dried enzyme preparation 

 and succinate was not inhibited by the toxins. Furthermore the 

 presence of 1 : 3000 of methylene blue, acting as an "oxygen carrier," 

 reduced the inhibition of aerobic oxidation of succinate by toxin from 

 78 to 44 per cent. 



The minced small intestine gave a very strong positive reaction for 

 indophenol oxidase, although it was practically unaffected by the 

 addition of the toxin of CI. welchii, type A, but was inhibited by cya- 

 nide which is a specific heme-enzyme inhibitor. On the basis of these 

 findings the authors stated that "These results, together with the 

 aerobic oxidation of succinate by small intestine in the presence of 

 toxin and methylene blue suggest that the inhibitory action of the 

 toxin is not exerted directly either upon the dehydrogenase or upon 

 . the oxidase but may be associated with an interference to some inter- 

 mediate link, possibly with an inactivation of some carrier catalyst.' " 

 They emphasized the fact that such interference by bacterial toxins 

 might facilitate the subsequent invasion of the body by the toxigenic 

 organism itself or by some other organism present at the time. This 

 was compared with the absence of certain vitamins, e.g., lactoflavin 

 or ascorbic acid, associated with the respiratory mechanisms of cells, 

 leading to grave disease. 



b. Neutralization of the Inhibition of Tissue Respiration by 

 Toxin as a Measure of the Antitoxin Concentration of Immune 

 Serum. Wooldridge and Higginbottom (1938), as discussed above, 

 showed that a-toxin of CI. ■welchii inhibited the oxidation of succinate 

 by tissue. This inhibition was neutralized completely by specific anti- 

 toxin. 



Of the antisera used, only those for the three types of CI. welchii, 

 A, C, and D, contained antibodies for the a-toxin. The type A anti- 

 toxic serum contained 300 units of a-antitoxin per ml.; type C anti- 

 serum contained 120 units of a-antitoxin and 900 units of /^-antitoxin 

 per ml.; and type D antiserum contained 85 units of a-antitoxin and 

 275 units of the e-antitoxin per ml. When these three antitoxins were 

 added in amounts equivalent in a-antitoxin units, they each reduced 

 the inhibitory effect of the type A toxin by about half, as shown in the 

 following table. 



