ANTIBODIES TO PNEUMOCOCCUS 401 



showed that the A carbohydrate was far more effective as an anti- 

 bactericidal — that is, antiopsonic — agent than deacetylated de- 

 rivatives of the capsular polysaccharide. 



OPSONINS IN PNEUMONIA 



Among others, Rosenow (1906) 1160 announced that the content 

 of opsonins for Pneumococcus appeared to be less in the serum of 

 patients succumbing to pneumonia than it was in normal human 

 serum or in serum of patients during or after crisis. Using the 

 Neufeld technique, Strouse (1911) 1346 could demonstrate no phago- 

 cytosis of virulent pneumococci by serum obtained from pneu- 

 monia patients after crisis, but by sensitizing the organisms with 

 convalescent serum previous to the test, phagocytosis was ob- 

 served in about one-fourth of the cases. Eggers (1912), 349 employ- 

 ing the plate method of cultivation, noted an increase in the pneu- 

 mococcidal power of the blood of pneumonia patients at or near 

 the time of crisis, and while he demonstrated that the action was 

 due to phagocytosis, Eggers presented no detailed experimental 

 evidence to prove whether the action of serum was exerted on the 

 cocci or on the leucocytes. Clough (1913) 240 observed that the se- 

 rum of approximately one-half the pneumonia patients obtained 

 after crisis or lysis exhibited definite phagocytic activity, and that 

 the reaction was strictly limited, under the conditions of the test, 

 to the homologous strain of Pneumococcus isolated from the pa- 

 tient whose serum was being examined. Clough concluded that, 

 since the active substances resisted heating at 56° and persisted in 

 the serum in vitro for a considerable period of time, the substances 

 must be tropins and, since phagocytic activity of the serum ap- 

 peared to parallel closely the protective power for mice in inci- 

 dence, time of appearance, and strain specificity, the protective 

 action of serum was directly due to its ability to promote phago- 

 cytosis. In a second report, Clough (1919) 242 confirmed his earlier 

 observations and added that while in 85 per cent of cases of acute 

 lobar pneumonia the serum showed positive phagocytic activity 



