THERAPEUTIC IMMUNIZATION IN MAN 449 



people have sufficient amounts of diphtheria antitoxin in their blood. 

 After the age of 40 an increasing percentage is without such protec- 

 tion. The first observation, that newborn children usually possess 

 considerable amounts of antitoxin, is very probably due to passive 

 immunization by the blood of the mother, a fact which we have men- 

 tioned in another place. The exact method by which such measure- 

 ments are made is described in a subsequent section on the intra- 

 cutaneous method of determining toxin and antitoxin. 



The work of Schick, that of J. Henderson Smith, and recent 

 studies by Park and Biggs promise to alter considerably the methods 

 of antitoxin therapy as at present in use in diphtheria. Smith meas- 

 ured the speed of absorption of antitoxin injected subcutaneously into 

 the abdominal wall of a healthy man. His results are shown in the 

 following table, which we take from his communication (page 213) : 



TABLE V 



One c. c. of the patient's serum contained: 



Before injection No demonstrable antitoxin 



5 hours after injection 0.1 unit antitoxin 



14 hours after injection 0.225 unit antitoxin 



32 hours after injection 0.68 unit antitoxin 



44 hours after injection 1.0 unit antitoxin 



3 days after injection 1.3 units antitoxin 



4 days after injection 1.3 units antitoxin 



6 days after injection . 68 unit antitoxin 



13 days after injection . 17 unit antitoxin 



15 days after injection . 14 unit antitoxin 



20 days after injection . 08 unit antitoxin 



27 days after injection No demonstrable antitoxin 12 



Park and Biggs 13 have made similar studies and have contrasted 

 the speed of absorption after subcutaneous administration with that 

 after intravenous injection, basing their curves upon careful measure- 

 ments of the sera of the treated patients. We reproduce their 

 charts as given in their recent publication. 



It is apparent from these charts, as well as from the work of Hen- 

 derson Smith, that antitoxin, subcutaneously given, is slowly ab- 

 sorbed, and does not reach its maximum concentration in the blood 

 stream until forty-eight hours or more after the injection. It fol- 

 lows that, as Park and Biggs point out, it is more rational to inject 

 a single adequate dose than to divide the dosage and inject at inter- 

 vals. They have obtained results in animal experiment which 

 graphically illustrate this principle. A rabbit which had received 

 ten fatal doses of toxin intravenously was given a total of 500 anti- 

 toxin units in divided doses as follows : 100 units after twenty min- 



12 J. Henderson Smith. Journal of Hygiene, Vol. 7, 1907, p. 205. 



13 Park and Biggs. Collected Studies from the N. Y. Department of 

 Health, Bureau of Laboratories, Vol. 7, 1912-1913, p. 27. 



