Non-fixation of Complement. 



15 



mune goat and complement from a normal goat) in connection with 

 the following antigen-antibody combinations : ( 1 ) meningococcus-anti- 

 meningococcus serum of Flexner (horse), (2) human-antihuman 

 serum (rabbit), (3) egg-albumen-antiegg-albumen (rabbit), and 

 finally (4) "syphilitic antigen" — syphilitic serum (or Wasser- 

 mann reaction). With the combinations of (1), (2) and (3), pre- 

 cipitates were first produced, then washed in saline solution by 

 centrifugation, and finally, before use were resuspended in saline 

 solution. That these different precipitates as well as the syphilitic 

 serum with "syphilitic antigen" were not inactive was easily dem- 

 onstrated by using another hemolytic system. Thus, when the 

 antihuman amboceptor derived from rabbit and complement from 

 guinea-pig or even from goat were used there was complete fixa- 

 tion in each instance. Again, it ivas subsequently found that when 

 the antihuman amboceptor derived from this goat is added to these 

 tubes in which complete fixation is beautifully shown by the use of 

 the antihuman amboceptor from rabbits, hemolysis ensues. There 

 is in such cases retardation in the hemolytic process, but it finally 

 becomes complete. It suggests strongly that these complements 

 are readily fixed by these precipitates or by syphilitic serum and 

 lipoids and remain there inactive in the presence of the amboceptor 

 derived from rabbit, while they become once more detached when 

 the amboceptor from goat is introduced. It is difficult, however, 

 to exclude another possibility, namely, that these sera contain one 

 fixable and one non-fixable set of complements. The former set 

 alone is in action when the amboceptor from rabbits is used, thus 

 explaining the absence of hemolysis in this instance ; while the 

 latter set is in operation with the other amboceptor (goat), and, 

 therefore, no fixation phenomenon can occur here. Whether this 

 peculiarity is common to the antihuman amboceptor derived from 

 all goats or simply an exception with this goat, I am unable to 

 answer. 



The foregoing observations warn one against an indiscriminate 

 generalization of the Bordet-Gengou fixation phenomenon and 

 require one to adopt that hemolytic system which is experimen- 

 tally proven to be suitable for demonstrating the fixation of com- 

 plement. The reactivating faculty of a complement has no bear- 

 ing on its fixation by the antigen-antibody combinations. 



