TOXINS AND ANTITOXINS 261 



Harrison (1932) reports the results he obtained by retesting 

 the children in the Washington schools, who had been immunized 

 against diphtheria. He states that 64 per cent were successfully 

 immunized by three injections of toxin-antitoxin. From a review 

 of the literature he concludes ''that 70 per cent successful im- 

 munizations from 3 injections would be a fair estimate of the 

 general effectiveness of toxin-antitoxin mixture." He suggests 

 that the wide variation in effectiveness reported by various 

 workers is probably due to the use of deteriorated toxin-antitoxin 

 mixtures and the variation in the strength of the toxin used in 

 the Schick test. Owing to the slowness with which immunity 

 develops, it is obvious that toxin-antitoxin cannot be used in the 

 treatment of diplitheria nor to give immediate protection such 

 as is afforded by passive immunization with antitoxin. 



Detoxified. Toxin.— The early work on the use of detoxified 

 toxin in immunization experiments on the lower animals is re- 

 ferred to by Pick (1908), Madsen (1908) and Loeffler (1913), 

 Dean (1913), Glenny (1931) and Zinsser (1931). They review 

 the literature and give excellent discussions of active immunity 

 to diphtheria produced by both toxin-antitoxin mixtures and de- 

 toxified toxins or toxoids. Apparently Behring (1890) and 

 Frankel (1890) working in Koch's laboratory succeeded in im- 

 munizing animals with toxoid. The former treated toxin with 

 iodine trichloride, while the latter attenuated it by heat (60° C). 

 According to Rosenau and Anderson (1908), Burchard (1895) 

 and Anderson (1907) showed that formalin would detoxify tetanus 

 toxin. It remained, however, for Glenny and Sudmersin (1921) to 

 determine experimentally for the first time that diphtheria toxin, 

 completely detoxified by the action of formaldehyde, retains its 

 antigenic property. According to Park and Schroder (1932) 

 Ramon "adopted the suggestions of Glenny as to the use of 

 formalin, and of Loewenstein of Vienna as to the value of nontoxic 

 toxoid in tetanus" and developed a satisfactory nontoxic diph- 

 theria toxoid. He uses only a toxin of high potency to which 

 he adds sufficient formalin (according to Glenny, 1931) to make 

 a concentration of 0.3 to 0.4 per cent. The formalized broth 

 culture containing toxin and bacteria is incubated for one month 

 at 37° C. It is then sterilized by filtration and its toxicity de- 

 termined. It should be detoxified to the extent that 6.0 cubic 



