THERAPEUTIC IMMUNIZATION IN MAN 455 



1 Antitoxin unit + 0.23 c. c. = fatal in 17 days 



1 Antitoxin unit -j- 0.24 c. c. = fatal in 14 days 



1 Antitoxin unit -f 0.26 c. c. = fatal in 9 days 



1 Antitoxin unit -j- 0.28 e.c. = fatal in 6 days 



i Antitoxin unit + 0.29 c. c. = fatal in 4 days = L+ 



1 Antitoxin unit + r3~"c. c. = fatal in 3 days 



The production of antitoxin is carried out by the graded injec- 

 tion of antitoxin into horses. Young, healthy horses are chosen, 

 tested for freedom from glanders, and the first injections are made 

 either with toxin attenuated by the addition of Lugol's solution or 

 terchlorid of iodin, or, as in the New York Health Department, the 

 first injections consist of mixtures of toxin and antitoxin. We take 

 our description largely from the account given by Park. 22 The first 

 injection consists of 12 c. c. of toxin (M L D 1/400 c. c.), together 

 with 100 units of antitoxin. After the reaction from such an injec- 

 tion has completely subsided after 3 to 5 days a second injection 

 is given of toxin without antitoxin; then 15 c. c., 45 c. c., 55 c. c., 

 65 c. c., 80 c. c., 95 c. c., 115 c. c., 140 c. c., etc., the intervals be- 

 tween injections being about three days and depending upon the 

 reaction of the horse and the speed with which it entirely recovers 

 from the preceding injection. In a particular case cited by Park 

 675 c. c. of toxin could be given by the 60th day ; in this case by the 

 28th day the horse was yielding 225 units to the c. c. ; on the 40th 

 day, 850 units ; on the 60th day, 1,000 units. 



The determination of the antitoxin unit, carried out from time 

 to time on the serum of such a horse against the L+ dose described 

 in our preceding table, would be carried out as follows : 



In all such standardization great care must be taken in employ- 

 ing accurately standardized glassware. Rosenau recommends em- 

 ploying "capacity instruments" rather than "outflow instruments." 

 Dilutions of unknown antitoxin are made in 0.85 per cent, sterile 

 salt solution. As a basic dilution one part of the antitoxic serum to 

 nine of the salt solution gives 1/10 c. c. to each cubic centimeter, 

 and from this initial dilution further dilutions may be easily made 

 as follows : 1 c. c. of dilution L + 9 c. c. salt solution = 1-100, etc. 

 A series of mixtures is then made in each of which the quantity of 

 toxin equals the L + dose, and in which the quantity of antitoxin 

 varies within a wide margin of the limits of strength to be expected. 

 This is illustrated in the following table : 



L+ (0.29 c. c.) + 1/500 c. c. of antitoxic serum = lives 



L+ (0.29 c. c.) 4- 1/600 c. c. of antitoxic serum = lives 



L + (0.29 c. c.) + 1/700 c. c. of antitoxic serum = lives 



L + (0.29 c. c.) + 1/800 c. c. of antitoxic serum = dies in 8 days 



L + (0.29 c. c.) + 1/900 c. c. of antitoxic serum = dies in 4 days 



L+ (0.29 c. c.) 4- 1/1,000 c. c. of antitoxic serum = dies in 2 days 



22 Park and Williams. "Pathogenic Bacteria," p. 213. 



