452 H^EMOLYSINS AND ALLIED BODIES 



haemolysis ; that is to say, if mixed with the fresh serum of eel's 

 blood, and the mixture added to susceptible erythrocytes, 

 no haemolysis will follow. Just as the injection of a toxin 

 causes a specific antitoxin to be produced in the injected animal's 

 blood, so does the injection of haemolysin produce an anti- 

 hsemolysin. 



The same thing happens if an artificial hsemolysin be employed. 

 Thus, if the serum of a guinea-pig which has received several 

 injections of rabbit's blood be repeatedly injected into a rabbit, in 

 gradually increasing dosage, this rabbit's serum will, after some 

 time, acquire the property of inhibiting the hsemolytic action of 

 immunised guinea-pig's serum on rabbit's erythrocytes. These 

 results are quite what might be expected from what we have 

 learned above ; curiously enough, however, the strongest anti- 

 hsemolysin can be produced by injecting the haemolytic serum into 

 an animal whose erythrocytes are not readily haemolysed in vitro by 

 that serum. Thus a very strong anti-haemolysin can be produced 

 in a rabbit by injecting it with a serum rendered haemolytic 

 towards ox's erythrocytes. The receptors which form the anti- 

 haemolysin in this case must be derived from cells other than the 

 erythrocytes (i.e. from extra vascular cells). 



As indicated by the side-chain theory, there are three possible 

 ways by which anti-haemolysins may be produced : there are three 

 haptophoric groups concerned in haemolysis, one belonging to the 

 complement and two to the amboceptors ; each of these may anchor 

 on to receptors in the organism, and so lead to the liberation into 

 the blood of similar receptors which, as we have seen above, will 

 be capable of neutralising one or other of the three haptophoric 

 groups. This is explained in Fig. 23. 



Anti- amboceptors (AA in Fig. 23) have been described by several 

 workers. According to Ehrlich it is the cytophilic group which, 

 in this case, enters into the reaction. Of much greater importance, 

 however, are anti- complements (AC in Fig. 23), i.e. bodies which cover 

 over the haptophoric group of a complement and prevent it from 

 uniting with an amboceptor. Such anti-complements are produced 

 by inoculation of the complements of one animal's blood into 

 another animal. Since there are as many complements in normal 

 as in immune blood, anti-complements can be readily produced by 

 employing normal serum. The complement leads to the pro- 

 duction of anti-complement in that its haptophoric group unites 

 with receptors in the injected animal. These are then produced 



