484 Inhibitory Action upon Phagocytosis, etc. 



Cocci per leucocyte. 



Test fluid "T" 10*7 



Control fluid "C" 157 



(Opsonic content with regard to B. tuberculosis omitted.) 



The difference between " C" and "T" is thus relatively small. A similar experiment 

 was made, in which staphylococci, which had been heated at 60° C. for 1 hr. 30 mins., were 

 passed through normal heated serum. Result : — 



. Cocci per leucocyte. 



Test fluid "T" 20 



Control fluid "C" 18 



So far, then, as these latter experiments are concerned, it does not appear 

 that much, if any, inhibitory action on fresh normal serum is exerted by heated 

 serum through which staphylococci have been passed. In view of the con- 

 sistent results obtained with tubercle bacilli in the first series of experiments, 

 it was important to determine whether saline solutions, through which bacilli 

 have been passed, exhibited a similar inhibitory action on fresh normal 

 serum. 



A saline solution (1 : 1000) was digested at 37° with tubercle bacilli for 

 1 hr. 30 mins. and then centrifugalised. The extract so obtained was added 

 in equal volume to fresh normal serum and kept at 37° C. for 1 hr. 

 A control fluid was made by digesting the normal serum with salt solution 

 (1 : 1000). The contents in tubercular opsonin of these two fluids were then 

 compared, with the following result : — 



Bacilli per leucocyte. 



Test fluid 5*4 



Control fluid 7'7 



Three similar experiments yielded the following figures :— 



Bacilli per leucocyte. Cocci per leucocyte. 



Test fluid 6*7 \ 5 1 11-9 \ 



Control fluid 10'6J 6 J 11'9-T 



Extracts of tubercle bacilli in salt solution have, therefore, little, if any, 

 inhibitory action on the tubercular and staphylococcal opsonins of fresh 

 normal serum. 



Conclusions. 



Heated normal serum, through which tubercle bacilli have been passed, 

 exerts a marked inhibitory action on the tubercular and staphylococcal 

 opsonins of fresh normal serum. Such an action points to the presence in 

 normal serum of opsonic amboceptors, the combination of which with the 

 free receptors thrown off from the tubercle bacilli deviates the complement 

 from the fresh normal serum, and thus inhibits phagocytosis. Further 

 experiments of this nature are in progress. 



