342 CYTOLYSINS 



of course, present in the various serums with which these observers were 

 working, but it was not until 1895 that Bordet showed quite clearly that 

 two substances were concerned in the phenomena of bacteriolysis and 

 hemolysis. At this time he demonstrated that the alexin or comple- 

 ment may be removed from a serum by heating it to 55 to 56 C., and 

 that it may be reactivated by the addition of fresh serum from another 

 .animal; that an old bacteriolytic serum cannot produce bacteriolysis 

 unless it is reactivated by a fresh normal serum or is placed in the peri- 

 toneal cavity of a living animal, from which it may derive the thermola- 

 bile alexin. In other words, the amboceptors in these serums with- 

 stood the effects of heating and age, but were unable to produce lysis 

 without the aid of an alexin furnished by a fresh normal serum. 



Structure of Amboceptors. According to the theory of Ehrlich, an 

 amboceptor is but a simple interbody furnished with two haptophore or 

 grasping portions. One haptophore group attaches the antibody to its 

 antigen, whatever that may happen to be bacterium, erythrocyte, 

 epithelial cell, etc., while the other attaches a suitable complement 

 (Fig. 95). The first is called the cytophile or antigentophile group, and 

 the second, the complementophile group. The amboceptor is specific 

 in the sense that it will unite only with its antigen or other very closely 

 related body. For example, when a rabbit is injected with sheep cor- 

 puscles an amboceptor is formed that will unite only with sheep, and 

 not with human, dog, ox, or other cells. 



As will be shown further on, Ehrlich believes that many different 

 complements may be present in a serum, whereas Bordet believes 

 that one complement exists that will act with the amboceptor, whether 

 this is bacteriolysin or hemolysin. This view is based mainly upon the 

 observation that the complement in a serum may be absorbed out by 

 furnishing an excess of either bacteriolytic or hemolytic amboceptors, 

 the one variety of amboceptor removing all the complement for the 

 other. Although the results of experimental work would seem to indi- 

 cate that Ehrlich's belief in the plurality of complements is correct, and 

 while this view is quite generally held, conclusive proof regarding this 

 has not as yet been furnished. An amboceptor may have more than 

 one complementophile group, and may bind a number of different com- 

 plements simultaneously (polyceptor) (Fig. 96). Ehrlich and Morgen- 

 roth called attention to this possibility when they stated: "Finally, it 

 is possible that an immune body, besides one particular cytophile group, 

 contains two, three, or more complementophile groups." Later Ehrlich 

 and Marshall showed that, in order to get a specific lytic effect, it was not 

 necessary for all complements to become active, but that only a few 



