392 BIOLOGY OF PNEUMOCOCCUS 



ence of immune opsonins in the serum of pneumonia patients. The 

 addition of the serum accelerated the ingestion of pneumococci by 

 the white cells. 



In 1915, Friel 494 described the action of normal and immune 

 serum on pneumococci. Cultures left in contact with normal serum 

 for one and one-half to twenty-four hours and then washed in 

 salt solution acquired no increased susceptibility to the action of 

 phagocytes, but organisms similarly treated with immune serum 

 were avidly ingested by the white cells. It will be recalled that the 

 sensitizing effect of immune serum was called "piantication" by 

 Friel. The term, meaning to prepare for slaughter, was in effect 

 the same as Wright's word opsonization, meaning to prepare for 

 the feast. In addition to the action of opsonins in rendering pneu- 

 mococci susceptible to the destructive action of leucocytes, Good- 

 ner, Dubos, and Avery (1932) 538 demonstrated that organisms 

 denuded of capsule by the action of specific bacterial enzymes be- 

 came highly vulnerable to phagocytosis by tissue cells. 



In an endeavor to clarify the contradictory conceptions of Neu- 

 feld and Rimpau 997 on the one hand and of Romer* on the other re- 

 garding the action of immune serum on bacterium or leucocyte, 

 Preisz (1915), 1108 by employing normal and immune serum and 

 leucocytes in both in vitro and in vivo experiments, concluded that 

 the ability of immune serum to promote phagocytosis of pneumo- 

 cocci lay in its action on the cocci and not on the leucocytes. 



A more recent report — that of Robertson and Sia (1927) 1147 — 

 dealt with the action of the serum of both naturally resistant and 

 susceptible animals on the phagocytability of Pneumococcus. 

 When virulent cultures were sensitized by contact for one hour at 

 37° with the serum of animals resistant to Pneumococcus, the or- 

 ganisms were actively ingested not only by homologous leucocytes 

 but also by the white blood corpuscles of other resistant and sus- 

 ceptible animals. On the contrary, when pneumococci were exposed 

 to the action of the serum of animals normally susceptible to pneu- 



* Quoted by Neufeld and Haendel.992 



