770 PASSIVE IMMUNIZATION SERUM THERAPY 



Convention on International Medicine in 1913, is based upon the prin- 

 ciple that the union of toxin and antitoxin is not stable, and when a 

 neutral mixture of the two is injected into animals, sufficient toxin be- 

 comes dissociated to unite with body cells and stimulate the production 

 of antitoxin. 



The mixture of toxin and antitoxin is known as T.-A., and several 

 strengths are being used; of these, the first dose possesses the lowest 

 toxicity and is overneutralized by mixing 1 unit of antitoxin with 50 

 per cent, of the L+ dose of toxin; the second dose may be about neutral 

 or 65 per cent, of the L+ toxin with 1 unit of antitoxin; the third dose 

 is usually slightly toxic for the guinea-pig afid is prepared with 80 per 

 cent, of the L+ dose of toxin with 1 unit of antioxin. I generally 

 prepare these solutions in such proportions that the proper doses are 

 contained in 1 c.c. The following is an example of the preparation of 

 100 doses of each of the three mixtures with a toxin having an L-f- dose 

 of 0.2 c.c.: 



First dose: 50 per cent, of the L+ dose of toxin or 10 c.c. for 100 

 doses. 



Second dose: 65 per cent of the L+ dose of toxin or 13 c.c. for 

 100 doses. 



Third dose: 80 per cent, of the L-f dose of toxin or 16 c.c. for 

 100 doses. 



To each of these is added an amount of antitoxin serum equal to 

 100 units and sufficient sterile salt solution containing 0.25 per cent, 

 tricresol to make the total volume 100 c.c. After standing several hours 

 the toxicity of each mixture is tested by subcutaneous injections into 

 250-gram guinea-pigs. 



The dose of each mixture is 1 c.c. and the injections are given sub- 

 cutaneously at intervals of ten days. 



The method has now been used for immunizing a large number of 

 persons, chiefly under the supervision of von Behring and his assistants. 1 

 The natural antitoxin content of the blood is determined, usually by 

 the intracutaneous method on the guinea-pig, before and after immuni- 

 zation, and has shown uniformly a considerable increase, which persists 

 over many months. 



Local and general reactions have been observed, especially in older 

 children and adults with doses intended for the new-born; this fact is 

 explained on the assumption of a specific sensitization in consequence 



1 See Semaine Me"dicale, 1913, xxxiii, No. 18; Berl. klin. Wochenschr., 1914, 

 hx, 917; ibid., 1914, lix, 917; Therap. Monatssch., 1913, xxvii, No. 11; Deutsch. med. 

 Wchnschr., 1913, xxx, 460; ibid., 1913, xxix, 977; ibid., 1913, xxxix, 1977; ibid., 1913, 

 xxxix, 2500; ibid., 1914, xl, 13; ibid., 1914, xl, 582. 



