Immunization with Sensitized Bacteria. 103 



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Immunization with sensitized bacteria. 

 By Homer F. Swift and Ralph A. Kinsella. 



[From the Medical Clinic of the Presbyterian Hospital.] 



The object of the present study was to determine the relative 

 immunizing property of various preparations of green strepto- 

 cocci. Two different strains of green-forming streptococci were 

 used, both isolated from cases of acute rheumatic fever. The lethal 

 dose of these organisms for mice, was from 0.1 to 0.5 c.c. of a 

 twenty-four hours broth culture. The sensitized vaccine was 

 prepared from a twenty-four hours broth culture, centrifugalized, 

 washed, killed at 56 0 , strong anti-serum added, incubated one hour, 

 washed and suspended in saline. Sensitized vaccines were always 

 freshly prepared. Three different antibodies have been studied, 

 agglutinins, complement fixing bodies and protective antibodies. 

 Rabbits were immunized by first injecting dead organisms, later 

 by living organisms and the comparative curve of antibody for- 

 mation studied. With unsensitized vaccine there was strong 

 formation of antibodies in from twelve to sixteen days, the curve 

 for agglutinins, complement-fixing antibodies and protective anti- 

 bodies running parallel. The animals immunized or rather in- 

 jected with sensitized vaccines showed at times a late formation 

 of weak agglutinins or complement-fixing antibodies. In no case 

 have animals injected with sensitized vaccines shown the presence 

 of protective antibodies. The protective antibodies we tested 

 by injecting diminishing quantities of the rabbit serum with 

 lethal doses of bacteria into mice. 



Our conclusions from this experiment are that it is impossible 

 to demonstrate the presence of antibodies in rabbits immunized 

 with sensitized vaccines either living or dead. These results 

 cannot be applied to immunization with all varieties of bacteria, 

 because at present work in progress shows that agglutinins may 

 be induced by the injection of sensitized pneumococci. 



