AMBOCEPTORS 321 



are necessary in any single instance to bring about effect. These com- 

 plements are termed ''dominant complements," the remainder being 

 known as "non-dominant complements." 



Whether amboceptors can undergo degenerative changes and lose 

 their cytophile or complementophile groups and become amboceptoids, 

 just as toxoids and agglutinoids are formed, is still doubtful. Reasoning 

 from analogy to the toxins and agglutinins, it is probable that ambocep- 

 toids may be produced by a loss of the complementophile group, the 

 cytophile portion of all antibodies being more stable; such ambocep- 

 toids, by uniting with their antigens, may effectually block the action 

 of an amboceptor, just as agglutinoids prevent agglutination. 



General Properties of Amboceptors. Amboceptors are fairly re- 

 sistant bodies, withstanding to a well-marked degree the effects of heat, 

 acids, alkalis, exposure, and drying. A 

 hemolytic serum, for instance, may be pre- 

 served in a sterile condition for many 

 months and show but slight deterioration 

 in its activity. Such a serum may be dried 

 in vacuo or on suitable filter-paper, and 

 preserve its activity for remarkable inter- FIG. 93. THEORETIC STRUC- 



' ,. .,, , ,. , , , , , TURE OF A POLYCEPTOR. 



vals of time, with but slight and gradual Af ^ain portion of am- 



deterioration. While a temperature of 55 boceptor in combination with 



. . a cell; C. dominant comple- 



C. will inactivate complement in from men t; c, lesser complements. 



fifteen to thirty minutes, amboceptors can 



tolerate from 60 to 65 C. for an hour and show but slight depreciation 



in activity. 



Mechanism of the Action of Amboceptors. An amboceptor or anti- 

 body of the third order is believed to act as a simple chemical interbody 

 between antigen and complement i. e., it is a connecting link between 

 the two. Complement is, therefore, the active agent in lytic processes, 

 but is practically powerless to act upon the antigen until brought into 

 chemical union through the intervention of an amboceptor. Comple- 

 ment is present in normal serums, and its quantity cannot be increased 

 by immunization. , Amboceptors are specific for their antigen, may be 

 present in small amounts in a normal serum, but may be greatly in- 

 creased during infection or as the result of artificial immunization. A 

 hemolytic amboceptor for sheep corpuscles is specific for these, and will 

 not unite with the corpuscles of any other animal. A bacteriolytic 

 amboceptor as for Bacillus typhosus will unite only with those bacilli, 

 and to a lesser extent with closely related bacilli, such as the paratyphoids 

 21 



