248 PASSIVE IMMUNIZATION 



early date, and where the serum can be conveniently and system- 

 atically tested. In the other streptococcus infections the bacterio- 

 logical diagnosis is frequently not made at all, or it is delayed until 

 it would seem unreasonable to expect any favorable result. Here, 

 as elsewhere, in serum therapy, the clinician should bear in mind 

 that the greatest good will only be accomplished, if the various anti- 

 sera are used early, in sufficient quantity, and usually in repeated 

 doses. 



Mode of Action. Regarding the mode of action of the various 

 antistreptococcus sera, it would seem that this is to a great extent 

 bacteriotropic in character, for whereas in unprotected animals 

 an intraperitoneal inoculation with an appropriate number of organ- 

 isms is followed by a relatively insignificant hyperleukocytosis and 

 phagocytosis, while the organisms multiply without any very evident 

 restraint, the treated animals show exactly the opposite picture, 

 i. e., extensive hyperleukocytosis and phagocytosis without evidence 

 of multiplication. The same can be shown outside of the body, 

 directly under the microscope; for whereas in the presence of normal 

 serum, washed leukocytes will scarcely take up any virulent strep- 

 tococci, they do so readily when in contact with immune serum. 



Whether or not bacteriolytic processes also play a role in the 

 protection of the animal with suitable immune sera is still a matter 

 of dispute. Antitoxins, on the other hand, certainly are not present. 



Preparation and Standardization. The preparation of the antistrep- 

 tococcus sera is conducted essentially on the same lines as that of 

 other non-antitoxic sera, viz., by starting the immunization with 

 small doses of killed-off cultures and progressively increasing the dose, 

 until finally full virulent living organisms are injected. At the 

 Serum Institute of Vienna, bouillon cultures of from two to eight 

 days' growth are used, the initial dose being 0.5 c.c., and the final 

 one varying between 100 and 200 c.c., all the injections being given 

 subcutaneously. The animals are not bled until the immunization 

 has been continued for about six months. The serum is then tested 

 in reference to its bacteriological purity and titer, and finally put up 

 in doses of 50 and 100 c.c. each, without any preservative. 



In making up the polyvalent antigen for immunization, it is con- 

 venient, even though all the other strains be of human origin and 

 not passed through animals, to introduce one strain which has been 

 so treated and brought to a high degree of virulence, for mice for 



