236 PASSIVE IMMUNIZATION 



MORTALITY ACCORDING TO AGE AND PERIOD OF INJECTION. 



2. Streptococcus Immune Sera. The role of the streptococcus in some diseases, for 

 example, scarlet fever, is imperfectly understood. Moreover it has only been in- 

 definitely established whether there are various groups or only one kind of strepto- 

 coccus; even the significance of their virulence or hemolysin formation is not clear. 

 These difficulties account for the great number of methods advocated for the pro- 

 duction of an immune streptococcus serum. The oldest, serum is that of Marmorek. 

 It was produced by immunization with a strain made highly virulent by passage 

 through animals. The other sera on the market are: 



a. Serum of Aronson (Schering). This is a polyvalent serum produced by immuni- 

 zation of horses with cultures pathogenic for man; some strains having previously 

 been passed through animals, others not. The strength of the serum is tested in mice 

 infected with the latter strains. 



b. Serum of Meyer-Ruppel (Hochst Farbwerke). Horses are first immunized with a 

 strain of streptococcus whose virulence has been raised by passage through horses and 

 mice; each horse is then injected with a different strain of human streptococcus. When 

 the serum of each animal is of such a strength that doses of o.oi to 0.0005 c.cm. protect 

 mice infected with its own particular strain, the sera of the different horses are mixed. 

 Thus a polyvalent serum is obtained. 



c. Serum of Menzer (Merck) is monovalent and produced by immunization with a 

 culture which is pathogenic for man and not passed through animals. 



d. Serum of Moser is polyvalent, produced by injections of streptococci from 

 scarlet fever. The sera of Menzer and Moser are not tested by injections of white mice. 

 The others are. One cannot strictly rely upon this method of serum titration for its 

 employment in man. The virulence of streptococci against mice and human beings 

 bears no definite relation. A serum may be perfectly efficient in mice both for prophy- 

 lactic and therapeutic purposes, and be entirely inactive in man; also vice versa. The 

 action of the serum should be in the main of bacteriotropic nature. 



Antistreptococcus serum has been tried in scarlet fever, puerperal sep- 

 sis, erysipelas, and articular rheumatism. 



Complement fixation experiments (Foix and Mallein, Schleissner) 



