IMMUNITY IN PNEUMOCOCCAL INFECTIONS 2$ 



Cocci per 

 leucocyte. 

 Normal serum + Normal leucocytes + Normal cocci - 19-1 



Normal serum heated to 



60° for 30 mins. + n 4. „ _ ^.3 



Supernatant fluid i pt. \ 

 Heated serum 2 pts. / "^ " + <- - 2-9 



Supernatant 2 pts. \ 



Heated serum i pt. / "^ " -f m - 3-2 



Supernatant fluid 3 pts. + „ + „ - 2*2 



The deposit was then made into an emulsion with normal saline, and 

 tested with normal leucocytes, which showed that the cocci were 

 opsonised, and, therefore, that the opsonin had passed from the serum 

 into the cocci. In haemolytic experiments, if a similar procedure is 

 undertaken at 0° C, there can be separated from the supernatant fluid a 

 complement which would give a reaction with heated serum. This is 

 evidently not the case with opsonin. It has been alleged by Crofton (3i) 

 that there are two bodies in normal serum contributing to opsonisation 

 of bacteria, one thermolabile corresponding to the complement, and the 

 other thermostable corresponding to the immune body. His experiments 

 do not give much support to this deduction. 



When bacteria are opsonised, heating for prolonged periods to 60° C. 

 is unable to destroy their power of being taken by the polymorphonuclear 

 leucocytes without the intervention of serum. When once opsonised it 

 is impossible to opsonise further, and opsonised cocci do not appear to 

 be capable of removing opsonin from normal serum. 



Cocci were opsonised by digestion at 37° C, and the mixture of 

 serum and cocci was heated to 60° for 30 minutes. The cocci were 

 centrifugalised down, and the deposit added to normal serum, and 

 allowed to stand for 30 minutes. The centrifugi was again applied, and 

 the supernatant clear fluid tested against normal serum. 



Normal serum + Corpuscles 4- Cocci = 1 1 '8 

 Supernatant fluid + n + " =11*2 



Thus, passing opsonised cocci through the serum does not rob it of any 

 of the opsonin contained. 



Is the increased opsonic power developed during immunisation of the 

 same nature as that of normal present in the serum ? 



(389) 



