OPSONINS AND VACCINE THERAPY 337 



Because of their action in preparing the bacteria for ingestion by the 

 leucocytes, he named those bodies "opsonins" (oif/uvtiv, to prepare 

 food). 



Neufeld and Rimpau 4 soon after, and independently of Wright, 

 described similar substances in the blood serum of streptococcus and 

 pneumococcus immune animals, which they called bacteriotropins. 

 Because of their greater thermostability it is not yet possible to 

 identify these bacteriotropins absolutely with the opsonins. 



The importance of these opsonic substances in immunity was 

 shown by Wright 5 in a series of experiments in which he determined 

 that in persons ill with staphylococcus or tubercle-bacillus infections, 

 the phagocytic powers were relatively diminished toward these 

 microorganisms, but could be specifically increased upon active im- 

 munization with dead bacteria or bacterial products. 



The results of Wright have been confirmed and elaborated by 

 numerous workers. 



The diminished power of leucocytes to take up bacteria without 

 the cooperation of serum was demonstrated, after Wright, by Hek- 

 toen and Ruediger, who worked with gradually increasing dilutions 

 of serum. The contention of the Wright school, however, that 

 leucocytes are entirely impotent for phagocytosis without the aid 

 of serum, can not be regarded as proven, in face of the work of 

 Lohlein 7 and others who have observed phagocytosis on the part 

 of washed leucocytes. 



The specificity of opsonins and their multiplicity in a given 

 serum were shown mainly by the work of Bullock and Atkin, 8 

 Hektoen and Ruediger, 9 and Bullock and Western. 10 These authors 

 showed that the opsonic substances in sera could be absorbed out 

 of the sera, one by one, by treatment with various species of bacteria, 

 a procedure analogous to the method of absorption used in the 

 study of agglutinins. 



The increase of phagocytic power demonstrated by Wright in 

 immune sera naturally led to the question whether this depended 



^Neufeld und Rimpau, Deut. med. Woch., xl, 1904. 



c Wright and Douglas, Proc. Eoy. Soc., London, Ixxiv, 1905. 



*Hcktoen and Euediger, Jour. Inf. Dis., ii, 1905. 



7 Lohlein, Ann. de Pinst. Pasteur, 1905 and 1906. 



8 Bullock and AtJcin, Proc. Eoy. Soc., London, Ixxiv, 1905. 



9 Hektoen and Ruediger, loc. cit. 



10 Bullock and Western, Proc. Roy. Soc., loc. cit. 



