XXVI. A CONTRIBUTION TO OUR KNOWLEDGE OF ANTI- 

 TUBERCULOUS SENSITIZERS. 



By DR. GENGOU. 



Since Bordet's researches on the mechanism of acquired im- 

 munity, our knowledge of the sensitizers (Ehrlich's amboceptors) 

 has come to be more and more definite. These substances, which 

 appear in the blood of inoculated animals during the course of 

 immunization, are, as we know, specific and have as a peculiar 

 property the power of fixing the alexin on that substance against 

 which the animal that furnishes the sensitizers has been immunized. 

 The alexin of normal serum alone has little or no tendency to be- 

 come fixed on bacteria or red blood cells ; a bacterium or red blood 

 cell which has been affected by its specific sensitizer has, on the 

 contrary, the power of fixing a large amount of alexin, which then 

 disappears from the surrounding fluid. Certain bacteria, as the 

 cholera vibrio, show a morphological change as a result of this 

 alexin fixation brought about by the specific sensitizer; they form 

 granules and then dissolve. Sensitized blood cells are easily hemo- 

 lyzed by alexin. Many forms of bacteria show no marked mor- 

 phological change through the influence of sensitizer plus alexin. 

 But even these bacteria, when they have been treated with the 

 sensitizer, show the property, as do the more susceptible organisms, 

 of fixing the alexin. This property, then, of fixing alexin on a 

 cell is generalized and fundamental property in every sensitizer. 

 Through this property, Bordet and Gengou,f in 1900, were able to 

 demonstrate the presence of sensitizers in certain active sera. These 

 authors showed that the sera of animals that have been immunized 

 against the typhoid bacillus, the plague bacillus and the like, as 

 well as sera from patients who have recently recovered from typhoid 



* Zur Kenntnis der antituberkulosen Sensibilisatoren. Berliner klin. Wo- 

 chenschr., 1906, p. 1531. 

 t Page 217. 



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