CHAPTER XIII 



PRECIPITINS 



Introduction. — Shortly after Gruber and Durham (1896) and 

 Widal (1896) had demonstrated the relative specificity of bac- 

 terial agglutinins, Kraus (1897) discovered bacterial precipitins 

 and found them correspondingly specific. He mixed antieholera 

 inunune serum with the clear sterile filtrate from a broth culture 

 of the cholera vibrio and incubated the mixture at 37° C. After 

 a short time there appeared a cloudiness followed by flocculation 

 in the tubes. The precipitate settled out, after standing over- 

 night, leaving a clear supernatant fluid. He likewise found that 

 when he mixed a sterile filtrate from a broth culture of Eherthella 

 typJiosa with antityphoid immune scrum a precipitate developed. 

 When antityphoid immune serum w^as mixed with the filtrate 

 from vibrio cholera or when antieholera serum was mixed with 

 the filtrate from E. typhosa no precipitate developed. Thus Kraus 

 showed that the reaction is specific. 



Kraus' work was confirmed by Nicolle (1898) and extended 

 by Tchistovitch (1899) and Bordet (1899). The former immu- 

 nized animals with horse and eel serum and noted the develop- 

 ment of specific precipitins in their sera while the latter produced 

 precipitins for cow's milk. The following year Myers (1900) pro- 

 duced precipitins for crystalline egg albumen. 



Kraus named the antigen and antibody involved in this type 

 of reaction precipitiTwgen and precipitin respectively. This ter- 

 minology is similar to that used for tlie antigen and antibody 

 responsible for cellular agglutination where the former is called 

 the agglutinogen and the latter agglutinin (antibody). 



According to Uhlenhuth (1909), von Fish became interested in 

 Bordet 's observation that precipitins could be produced for cow's 

 milk and extended this by comparing the precipitins for cow's 

 milk and human milk. He concluded that these proteins could 

 be differentiated by the precipitin test. This work was confirmed 

 by Morgenroth (1900) and Wassermann ajid Schiitze. According 

 to Hektoen and Welker (1924), Leblanc (1901), working with 



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