174 CHEMISTRY OF THE IMMUNITY REACTIONS 



quite different from the antibody or antibodies resulting from immuni- 

 zation with non-toxic protein antigens, for there is some reason to 

 believe that the several types of reactions that may be accomplished 

 with the serum of animals immunized to foreign proteins or cells all 

 depend on one single antibody, which accomplishes the destruction of 

 the antigen by sensitizing it to the enzymes of the blood and tissues. 

 The neutralization of toxin by antitoxin is believed by many in- 

 vestigators to be a chemical process, which occurs as well in the test- 

 tube as in the body. It seems to occur according to the laws of definite 

 proportion, sl given amount of antitoxin neutralizing a proportionate 

 amount of toxin under equal conditions (hence the toxin is not de- 

 stroyed by antitoxin through a ferment action, as was at first suggested). 

 .Neither the toxin nor the antitoxin is destroj^ed in the process of neu- 

 tralization, as has been proved by suitable experiments, but they appear 



/to be chemically united to each other, as any two large molecules may 

 be. Pick and Schwarz believe that the union of toxin and antitoxin 

 takes place in two steps — first, colloidal adsorption, and then the specific 

 reaction. ^^ There is some question as to whether the union with anti- 

 toxin completes the neutralization of the toxin, or whether there is then 

 necessary a further destruction of the toxin in the body. But whether 

 necessary or not, such further destruction does take place. Neutrali- 



j zation occurs more rapidly under the influence of warmth, and more 

 slowly in the cold; and it is more rapid in concentrated than in dilute 

 solutions, just as with ordinary chemical reactions. It is said that it 

 requires two hours for tetanus toxin to be completelj^ combined with 

 the corresponding quantity of antitoxin at 37°. According to Arrhe- 

 nius and Madsen, reaction of antitoxin upon toxin is accompanied by 

 the liberation of much heat — 6600 calories per gram molecule, or about 

 half as much as is set free by the action of a strong acid upon a strong^ 

 base.^^ Union of toxin and antitoxin causes no change in the surface 

 tension of the fluid in which the reaction occurs (Zunz),*^ and the 

 neutral toxin-antitoxin compound (diphtheria) is not absorbed by ani- 

 mal charcoal, which absorbs each of the constituents when free. The 

 physico-chemical studies of the reaction between tetanolysin and its- 

 antibody gave results which led Arrhenius to conclude that in the 

 reaction there are formed from one molecule of toxin and one molecule 

 of antitoxin, two molecules of the reaction products (analogous to the 

 reaction between alcohol and acid which yields one molecule of ester 

 and one of water). In general, the union of toxin and antitoxin is 



"Also von Krogh (Zeit. f. Hyg., 1911 (68), 251). Bordet, Biltz, and others 

 look upon the neutralization of toxin as an adsorption process entirely. 

 g ** Literature of chemical and jihysical reactions of toxin and antitoxin given 

 ■ by Zangger, Cent. f. Bakt. (ref.), 1905 (80), 238; Arrhenius, "Ininiuno-cheni- 

 listry," 1907 and "(Quantitative Laws in Biological Chemistry," London, 1915;. 

 I also review in Zeit. Chemother., Kef., 1914 (3), 157; Oppenheimer and IMichaelis, 

 iHandbuc'li der Biochemie, Vol. II (1). 



^ 85 Bull. Acad. Royal i\Ied. Belg., 1911; also Bertolini, Biochem. Zeit., 1910 (28), 

 60. 



