114 IMMUNOLOGY 



nate an immunizing agent consisting of bacteria is not logical. 

 Usage, however, has led to the policy of applying the terra "vac- 

 cine" to practically all agents employed to produce active im- 

 munity. Agents used to produce passive immunity represent anti- 

 bodies present in or obtained from blood serum and are therefore 

 called sera, antisera or antibody solutions. 



Bacterial vaccines are employed for many specific purposes 

 which ma}' be enumerated as follows : 



1. Bacterial vaccines, especially typlioid vaccine, as well as 

 sterile milk have been used in norisi^ecific protein therapy in such 

 diseases as chronic gonorrheal rheumatism, various other types of 

 arthritis, psoriasis and some other conditions. They are injected 

 to produce a physiological reaction or protein shock in the patient. 



2. Specific vaccine therapy has been employed in certain recur- 

 rent or chronic diseases such as acne vulgaris, gonorrheal arthritis, 

 undulant fever, etc. The results reported are not very encourag- 

 ing. Since bacteria have not been incriminated as the cause of the 

 common cold one cannot regard the so-called "cold vaccines" as 

 specific. It is interesting to note that when these "cold vaccines" 

 have been tried out on a fairly large scale and under at least partly 

 controlled conditions, the results have been disappointing. 



3. Specific vaccines are injected into animals such as the horse, 

 ox, goat and rabbit to stimulate the production of specific humoral 

 antibodies. The animals are bled and the serum containing anti- 

 bodies is separated from the cellular elements. In the commercial 

 preparation of therapeutic and certain diagnostic sera the globulin 

 fraction of the serimi, containing antibodies, is precipitated, redis- 

 solved and concentrated. The most frequently used antibacterial 

 sera are those for the various t^-pes of pneumococci, meningococci 

 and streptococci. Antisera used to identify E. typhosa, the Sal- 

 vionell€^, various strains of dysentery and other bacteria are pro- 

 duced commercially, but they are frequently produced privately 

 and used without being concentrated. 



4. Bacterial vaccines are used quite extensively in prophylactic 

 immunizations against the organisms causing t}T)hoid fever and 

 whooping cough. Typhoid fever is one of the preventable diseases 

 that has decimated armies in the past. According to Jordan 

 (1931) 60 per cent of the German mortality during the Franco- 



