Pneumococcus Lesions of the Lobar Type. 



191 



Dr. W. L. Rost has assisted me in most of the experiments of 

 the present investigation. 



115 (1047) 



The effect of sensitization on pneumococcus lesions of the lobar 



type in rabbits. 



By Mary B. Kirkbride. 



[From the Laboratories of the N. Y. State Department of Health, 



Albany.] 



For the purpose of ascertaining to what extent conditions of 

 hypersusceptibility determine the character of pneumococcus 

 lesions of the lung, series of experiments were made with a moder- 

 ately virulent strain, and with an extremely virulent strain in its 

 virulent state and after artificial attenuation. Rabbits were 

 inoculated intravenously for purposes of sensitization with .1-15 

 c.c. pneumococcus filtrates or dead cells and then after two weeks 

 injected tracheally with 1. c.c. live cultures. The animals surviving 

 48 hours were killed. Microscopic sections were made of all lungs. 



In these experiments with attempted active sensitization none 

 of the animals developed symptoms resembling anaphylactic 

 shock nor was the lung involvement definitely increased in any 

 series of previously treated rabbits. Tracheal injection of the 

 moderately virulent organisms, however, caused marked lesions 

 in both sensitized and unsensitized control rabbits. 



In experiments with attempted passive sensitization, mixtures 

 of 1 c.c. virulent or attenuated live cultures and .1 c.c. or .5 c.c. 

 sera from normal or immunized rabbits when injected tracheally 

 failed to incite uniformly extensive lesions in any series of animals 

 though the proportion developing diffuse involvement was greater 

 than in the previous experiments with active sensitization. Sud- 

 den paroxysms, similar to those of fatal anaphylactic shock were 

 observed about twenty-four hours after tracheal injection in 

 practically all the animals of two or three experiments. But these 

 paroxysms were not associated with extensive lesions of the lung 

 because in a number of the rabbits no characteristic exudative 

 pneumonias were found, although the lungs were almost invariably 

 deeply conjested. 



