CHAPTER XIII 



FACTORS DETERMINING PHAGOCYTOSIS 



OPSONINS, TKOPINS 



FROM the very beginnings of his researches upon phagocytosis 

 Metchnikoff recognized that the process was profoundly influenced 

 by the properties of the fluid constituents of the blood plasma in 

 which the phenomenon occurred. Both he and his pupil Bordet, 1 

 at this time working in Metchnikoff's laboratory, noticed that the 

 phagocytic activity of leukocytes was greater in immune than in 

 normal sera and associated this with the specific properties of the 

 immune substances or antibodies in these sera ; Metchnikoff himself 

 interpreted the phagocytosis-enhancing power of the serum as a 

 stimulation of the leukocytes and referred to the serum constituents 

 by which this effect was produced as "stimulins." A closer analysis 

 of the factors involved in this interrelationship, however, was not 

 attempted at this time by him or his pupils, although indirect ref- 

 erence was made to it in a number of articles emanating from this 

 school in the course of investigations on kindred problems of phago- 

 cytosis. Thus Gabritschewsky, 2 in 1894, published a paper on 

 "Leukocytose dans la Diphtheric/' in which he concluded that the 

 poison of diphtheria bacilli, among other harmful effects, diminished 

 the phagocytic power of the leukocytes, and that one of the beneficial 

 influences of the curative serum was to render these and other cells 

 "less sensitive to the bacterial poisons. 7 ' This may be interpreted 

 as indicating an assumption that the action of an immune serum in 

 increasing phagocytic activity rested rather upon its influence upon 

 the bacterial products than upon any stimulation of the phagocytes 

 themselves. However, in diphtheria the action of the leukocytes 

 was, even at this time, recognized as a merely secondary one, and 

 Gabritschewsky's results did not materially influence the "stimulin" 

 conception. 



The first extensive investigation which occupied itself directly 

 with these problems was that of the Belgian bacteriologists Denys 

 and Leclef. 3 The publication of these workers deals primarily with 



1 Bordet. Ann. de Vlnst. Past., 1895. 



2 Gabritschewsky. Ann. de I'Inst. Past.., 1894. 



3 Denys and Leclef. La Cellule, 11, 1895. 



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