HAEMOLYSIS AND PHAGOCYTOSIS OF RED BLOOD CORPUSCLES 1 7 



The last point to which reference will be made is the question of the 

 destruction of the opsonin by heat. Wright and Douglas (loc cit), as 

 well as Bulloch and Atkin (loc cit.) and Hektoen and Ruediger {^^\ 

 working with normal sera with Wright's method, found that this 

 substance was almost entirely destroyed by heat at 50° C. - 60° C. Dean 

 repeated this work not only with normal, but also with immune scrum, 

 using, however, a somewhat different mode of procedure, and found that 

 in normal, but especially in immune sera, there was less destruction than 

 the authors mentioned had supposed. 



The following experiment illustrates this point, and shows that the 

 more highly immune a serum becomes, the less is the apparent 

 destruction of opsonin. This experiment was only a trial one, directed 

 to find the relationship of the curves of haemolysis and phagocytosis to 

 one another. Owing to the fact that the author had perforce to abandon 

 this work, no further experiments on the point could be carried out, but 

 from the results it is evident that the higher the immunity becomes the 

 less was the apparent destruction of the opsonin. The opsonic action is 

 limited in two ways. On the one hand, a certain number of leucocytes 

 constantly seem to be incapable of exercising, or exercise only with 

 difficulty, the property of phagocytosis, and on the other the capacity of 

 the leucocytes is not unlimited, especially for bodies of the size of red 

 blood cells. Thus there are two limitations. Suppose, e.g., that in a 

 given case, 90 ^/^ of the leucocytes used for a test are capable of acting 

 as phagocytes. Now, a highly immune serum, even in the heated 

 condition may be so active, and make the erythrocytes so easy to engulf, 

 that 90 °/^ of the leucocytes may contain red blood cells. But although 

 the unheated serum may be much more powerful than the heated, yet it 

 cannot produce more phagocytes, since the limit (90%) has been reached 

 by the heated serum. The greater the opsonic content of an immune 

 serum is, the more will this limitation come into play. 



The method of experimentation was as follows : — A normal guinea- 

 pig was taken. Of its serum, one part was mixed in capillary pipettes 

 with one part of a 5 7o suspension of the washed red blood cells of the 

 rabbit and one part of washed human leucocytes. Phagocytic tests were 

 then performed in the usual way. The percentage of leucocytes 

 containing blood shadows was counted in the case of heated as well as 

 unheated serum. At the same time serum of a control normal 



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