OPSONIC INDEX AND VACCINE THERAPY 343 



case of this bacillus opscmic investigations can be looked upon as 

 indicators of immunity with as much confidence as in cases of other 

 bacterial invasions. It is true, indeed, that tubercle bacilli as well 

 as leprosy, rat leprosy, and other acid-fast bacteria are eagerly 

 taken up by polynuclear leukocytes when they are injected into the 

 peritoneal cavity of a guinea pig or rat or other experimental ani- 

 mal. On the other hand, we have much evidence which seems to 

 show that such phagocytosis is not in these cases a direct method 

 of bacterial destruction. In another place we have cited the experi- 

 ments of Tschernorutski, 25 which showed that polynuclear leuko- 

 cytes, though containing other ferments, were devoid of lipase. And 

 Carey and the writer experimenting with rat leprosy bacilli found 

 that these acid-fast bacteria were not disintegrated within leukocytes 

 in the course of weeks, while they were often subject to rapid de- 

 struction in the presence of living spleen cells in plasma. Further- 

 more, in the discussion of the tuberculin tests we have reviewed 

 evidence which points to the fact that in the reactions to 

 tubercle bacilli we have probably to deal more particularly with 

 sessile receptors on fixed tissue cells than with specific circulating 

 antibodies. Bartel and Neumann 26 have concluded that the phago- 

 cyte which takes up tubercle bacilli represents only a preliminary 

 vehicle by which the micro-organisms are conveyed to the spleen and 

 lymphatic tissues, in which actual destruction then takes place. 

 While no final conclusions can be drawn from the available evidence, 

 all these data render it uncertain whether the opsonic index as de- 

 termined for polynuclear phagocytosis may be at all regarded as a 

 reliable indication of increased or diminished resistance, and on 

 this basis the control of therapy in tuberculosis by opsonin estima- 

 tions is of course placed upon an uncertain basis. 



We have then very briefly traced the work done upon opsonin 

 determinations from the purely practical point of view. There is 

 of course no question about the scientific accuracy of the observa- 

 tions upon which rests our knowledge of the opsonic properties of 

 blood serum. There is also no doubt concerning our ability to in- 

 crease the immunity of an individual by systematic treatment with 

 vaccines made of pure cultures of bacteria. However, the work of 

 Wright has concerned itself with two distinct questions which must 

 be separately answered. Briefly stated these are: 1. What is the 

 value of opsonic estimations in controlling the therapeutic vaccina- 

 tions of patients? 2. To what degree and in which particular 

 conditions may the process of vaccination (active immunization) be 

 regarded as a hopeful method of therapy ? 



25 Tschernorutski. Hoppe-Seyler's Zeitschr. f. Phys. Chem., Vol. 75, 

 1911. 



26 Bartel and Neumann. Wien. kl Woch. } Nos. 43 and 44, 1907 ; Cen- 

 tralbl. f. Bakt., Vol. 48, 1909. 



