262 IMMT'XOLOGY 



centimeters produce no symptoms, either local or general, when 

 injected siibcutaneously into a 300 gram guinea pig. Banzhaf 

 (1928) recommends filtering the toxin before adding formalde- 

 hyde. Moloney and Weld (1925) report that broth cultures of 

 C. diphtheriae are more readily detoxified by formalin than the 

 filtered toxin. Larson and Nelson (1924) and Larson, Halvorson, 

 Evans and Green (1925) have detoxified toxin with sodium 

 ricinoleate. They report successful immunization witli nontoxic 

 soap-toxin mixtures. 



Apparently phenol is not a satisfactory preservative for toxins. 

 Glenny states that any condition such as the shaking of dilutions 

 which favors the local concentration of phenol at the air-liquid 

 surface results in definite reduction in the antigenic value of the 

 toxin solution, iMoloney and Weld (1925) report that toxoids ob- 

 tained by treating phenol-preserved toxin witli formaldehyde fre- 

 (lUf'utly possess no antigenic value. 



Toxoid Specifications of U. S. Public Health Service.— Accord- 

 ing to Harrison* (1932) all toxoid manufactured or sold in tiie 

 United States must comply with the specification supplied l)y the 

 National Institute of Health of the U. S. Public Health Service. 

 He says that these specifications may be roughly stated as follows : 



"The toxin before detoxification must contain not less than 400 

 M.L.D.'s or 5L^ doses. Detoxification must be so complete that 

 5 human doses when injected into guinea pigs must show no sign 

 of early or late diphtheria poisoning. The antigenic efificiency 

 must be such that the initial human dose will immunize 80 per 

 cent of guinea pigs in 6 weeks to such a degree that 5 j\LL.D.'s 

 of toxin will fail to kill in 10 days." Park (1932) states that a 

 good toxoid should contain at least 8 antigenic or fiocculation 

 units per c.c. It is generally agreed that toxoid is a better im- 

 munizing agent than toxin-antitoxin. Harrison (1932) recom- 

 mends that at least 2 doses of 1.0 c.c. each be given with an in- 

 terval of from three to four weeks. The importance of this 

 interval of time is supported by the experimental work of Glenny 

 and Pope, Waddington and Wallace (1925). Wlien toxoid is 

 diluted, Park states that at least 4 antigenic units should be pres- 

 ent in the dose used for immunization. With 3 injections of 



*Harrlson, W. T. : Am. J. Pub. Health i^: 17, 1932. 



