IMPORTANCE OF OPSONINS. 331 



In pneumonia the greatest rise in the leucocytosis 

 appears to precede somewhat the highest rise of 

 the opsonin. In all these diseases the typical 

 wave-like opsonin curve is modified by the devel- 

 opment of complications of various kinds and at 

 the onset of which it commonly undergoes a dis- 

 tinct depression. In rapidly fatal cases, for in- 

 stance of pneumonia, the opsonic curve or index 

 may not return from the primary depression, but 

 sink lower and lower. In prolonged infections, 

 general as well as local, there occur irregular 

 fluctuations and in chronic, more or less stationary 

 cases, the opsonic index is often subnormal. At 

 this time further details cannot be given. My 

 chief point is to make clear the close association 

 between recovery and the wave-like rise of the 

 opsonin, and, as a result of the immunization in 

 all likelihood also of other antibodies, in the 

 typical attack of acute so-called self-limited in- 

 fections. In some of the diseases the opsonin is 

 the only antibody that we can measure readily 

 with our present means. As I have stated, an 

 intraphagocytic destruction of pneumococci and 

 streptococci takes place in the presence of fresh 

 leucocytes and opsonic serum, whereas either alone 

 constitutes a good medium for these bacteria. 

 Taking these facts into account it seems to me 

 that the wave-like course of the opsonin in pneu- 

 monia and in acute streptococcus infections is a 

 strong point on the side of the signal importance 

 of phagocytosis in their healing, whatever other 

 measure, of which at present we know less or 

 nothing, may be in operation also." 1 



1. Hektoen : Opsonins and Other Antibodies, Science, 1909. 



