262 



INFECTION AND IMMUNITY. 



Complement- 



opliilons 



Haptopliore 



of Ambocep- 



tor. 



Action of 

 Amboceptors. 



These results show the following important 

 facts: Amboceptor and complement exist side by 

 side in an immune serum, not as a united sub- 

 stance. Union of amboceptor with cell is inde- 

 pendent of complement,, the latter being taken up 

 only after the amboceptor-cell reaction has oc- 

 curred. Amboceptors unite with cells at a low 

 temperature, whereas complement requires a 

 higher temperature for its union and for the fer- 

 ment-like activity by which it dissolves or kills the 

 cells. 



That constituent of the amboceptor which 

 unites with the cell has been referred to as the 

 cytophilous haptophore. Ehrlich and his follow- 

 ers believe that complement in establishing con- 

 nection with the cells does so by combining with a 

 second haptophore of the amboceptor, after the 

 latter has sensitized the erythrocyte or bacterium. 

 Hence, an amboceptor has, as the name implies, 

 two receiving groups or haptophores, the second 

 being the complementophilous haptophore (Fig. 

 7). It is hardly desirable to discuss various ex- 

 periments which furnish additional evidence of the 

 amboceptor nature of the thermostabile body. The 

 observed phenomena allow one to assign to it the 

 two haptophores mentioned. 



There is a conflict of ideas as to the nature of 

 the change produced by the amboceptors, as a re- 

 sult of which the cells are made susceptible to the 

 action of complement. Bordet- speaks of the am- 

 boceptor as the substance sensibilisatrice, the sen- 

 sitizing substance; and his conception of the ac- 

 tion of the two substances he has compared rough- 

 ly to the opening of a lock for which two keys are 

 demanded. One key, amboceptor, is needed to 



