AMBOCEPTOR AND COMPLEMENT 207 



plenientary to that of the specific iininune body, it is called tlic com- 

 plement.^ 



It is believed that the action of these substances is as follows: The 

 ininiunc body is, like antitoxin, a cell receptor which unites the bac- 

 teria to the cell. It differs from the antitoxin, however, in that it has 

 two affinities, one for the complement and the other for the bacterial 

 substance. On account of the existence of the two affinities it is called 

 an amhoceptor. Some serums contain such amboceptors for certain 

 bacteria without previous immunization, hence the term im^mune 

 amboceptor is reserved for amboceptors developed by imnmnization. 



Amboceptor and Complement.'* — The function of the ambo- 

 ceptor is to unite the bacterial protoplasm, to which it is attached by 

 one affinity, to the complement which it holds by its other affinity, or, 

 to put it in a more strictl}^ chemical way, the addition of the ambocep- 

 tors to the bacteria gives them a chemical affinity for complement. 

 It is, therefore, an intermediary body, uniting the complement to the 

 bacterial protoplasm. The complement^ is the substance that actually 

 destroys the bacteria, in which respect, as well as in its susceptibility 

 to heat, it resembles the enzymes. Complement is present in normal 

 serums, and, as it is not increased in amount during immunization 

 it may not be sufficient to satisfy all the amboceptors, hence it may 

 be impossible to secure marked bactericidal effects even when many 

 amboceptors have been formed. If the complement in an immune 

 serum has been destroyed by heating, it may be replaced by adding 

 normal serum from another animal, even of some other species; indi- 

 cating either that the complement is not absolutely specific in its 

 nature, or that quite the same complement may be present in the 

 blood of many different animals. The origin of the complement is 

 unknown, but it has been urged that the leucocj^tes are an important 

 source of /this substance, if not its chief one;^ there is evidence, how- 

 ever, that various organs and cells may also produce complement.'^ 

 Its most important characteristics are its extreme susceptibility to 

 heat, and the resemblance of its action to the action of enzymes.^ 

 Hektoen^ found that it could be made to unite with Mg, Ca, Ba, Sr, 

 and SO4 ions, which rendered the complement (for typhoid bacilli and 

 red corpuscles) inactive. Man waring ^° found that these ions could be 



^ The polynuclear leucocytes also contain bacteriolj^tic agents, " endolysins, " of 

 a similar complex structure, but quite distinct from the serum bacteriolvsins (See 

 Kling, Zeit. Immunitat., 1910 (7), 1). 



■• See also Hemolysis, Chapter X. 



° Review and bibliography by Noguchi, Biochem. Zeit., 1907 (6), 327. 



^ Cholera antiserum will produce the Pfeiffer phenomenon of lysis of cholera 

 vibrios in animals made leucocj'te-free with thorium. (Lippmann, Zeit. Immuni- 

 tat., 1915 (24), 107.) 



' See Dick, Jour. Infect. Dis., 1913 (12), HI; and Lippmann and Plesch, Zeit. 

 Immunitat., 1913 (17), 548. 



« See Walker, Jour, of Physiol., 1906 (33), p. xxi. 



3 Trans. Chicago Path. Soc, 1903 (5), 303. 



10 Jour. Infectious Diseases, 1904 (1), 112. 



