ANTIBACTERIAL IMMUNIZATION 787 



More recently the possibilities of effecting active immunization 

 against hay-fever have been shown by Claves 1 with the pollen of rag- 

 weed. The method is still in the experimental stage, but it is reasonable 

 to assume that vaccines may be prepared for the pollen of various plants 

 usually responsible for the hay-fever and autumnal catarrhs of this 

 country. (See page 708.) 



ANTIBACTERIAL IMMUNIZATION 



General Considerations. It may be stated that antibacterial serums 

 have not been found of equal value to the antitoxins, . either in the 

 prophylaxis or in the treatment of their respective infections. It is 

 true, however, that antimeningococcus serum has reduced the mortality 

 of epidemic cerebrospinal meningitis from 75 to 90 per cent, to 30 per 

 cent, and less, and has thereby firmly established its value in the treat- 

 ment of this dreaded infection. Recent work in pneumonia has de- 

 veloped a method of serum therapy that has proved of value in the treat- 

 ment of this disease, and it is likewise true that antistreptococcus and 

 antigonococcus serums yield at times and in individual cases most 

 prompt and happy results. But the expectations for serum therapy 

 that were aroused in 1894 with the discovery of diphtheria antitoxin 

 have not been fully realized, although at the present time the reasons 

 for failure are being studied, understood, and gradually overcome. 



Granting that serum therapy could be reduced to the simple prop- 

 osition of bringing specific antibodies into relation with the micro- 

 organisms producing a given infection, the process remains quite intri- 

 cate, largely owing to the fact that although different strains of the same 

 microorganism may possess identical morphologic and biologic charac- 

 teristics, yet they vary not only in pathogenicity, but also in the speci- 

 ficity of the antibodies that they stimulate the body-cells to produce. 

 In other words, serum therapy is more specific than it is generally con- 

 sidered to be. For instance, the antibodies of one strain of pneumococcus 

 may have little or no action upon another strain, and the same is prob- 

 ably true of the various pathogenic bacilli and groups of streptococci, 

 gonococci, and to a lesser extent also of meningococci. This fact has 

 long been known, and an effort has been made to overcome the difficulty 

 by immunizing horses with a large number of different strains of the 

 same microorganism in the hope that the polyvalent serum so produced 

 would contain sufficient antibodies for all or most infections of the 

 various strains of the particular microorganisms in question. With 

 diphtheria and tetanus bacilli, the soluble toxin is apparently quite 

 1 Proc. Soc. Exper. Biol. and Med., 1913, x, 69. 



