lO QUATERCENTENARY STUDIES IN PATHOLOGY 



Relation of Fixateur to Opsonin. 



This subject acquired a fresh interest from its bearing on the work of 

 Wright and Douglas (^o), Bulloch and Atkin (^^) and others, on 

 phagocytosis. 



Wright and Douglas described the power which the blood serum has 

 of inducing the phagocytosis of micro-organisms as the "opsonic" 

 property, and the substance possessing this as the "opsonin," which, 

 in their opinion, was a substance not previously described, and which 

 acted on the micro-organisms or other bodies to be phagocytosed, 

 and not on the phagocytes. 



It was subsequently asserted by Dean (j^) and others that this was 

 not a new substance, but that it was identical with the fixateur, using 

 that term in the sense in which it was employed by Savtchenko, />., 

 regarding it as identical with the amboceptor. 



Barratt (^3), however, has since shown that the specific haemolytic 

 fixateur may be absent in an immune serum, and that, nevertheless, 

 a substance inducing the phagocytosis of red blood cells of the kind 

 employed for immunisation may be present. This substance he classed 

 with the "opsonins." 



The point at issue, then, is whether the substance which induces the 

 phagocytosis of red blood cells is identical with the specific haemolytic 

 fixateur or amboceptor, and the following experiments were carried 

 out with a view to elucidate this question. 



B.— EXPERIMENTAL. 



If the process of phagocytosis of red blood cells be due to the action 

 of the haemolytic amboceptor, as suggested by Savtchenko, then there 

 are two ways in which it may act. 



(i) It might act alone by attaching itself to the red blood cells, thus 

 rendering them liable to be phagocytosed. This theory is supported by 

 Savtchenko, Metchnikoff, Dean, &c. 



(2) It might, however, as Dean has also suggested, be aided in this 

 action by a complement, but if the complement were destroyed, might 

 still be capable in itself of inducing phagocytosis. 



(310) 



