Complement Fixation Method. 'JIJ 



or of their extracts. None of these methods are infallible. 

 They may, however, be supplemented so that doubtful results 

 given by one are rectified by a positive result obtained from 

 another method, thus the simultaneous application of several 

 methods v/ill reduce the errors to a very small percentage. 



Since the methods of serum diagnosis are all laboratory methods, it is neces- 

 sary for the practitioner to send suspected material, properly preserved, to a suit- 

 able laboratory for examination. For this purpose from 30 to 50 ccm. of blood are 

 drawn from the jugular vein (technic as in ordinary phlebotomy) into a sterilized 

 test tube. After supplying the tube with a cork to prevent infection, it is kept iu 

 a cool place for a few hours to permit separation of the serum from the clot, 

 whereupon it may be sent to the laboratory for examination. As a rule, results may 

 be reported within one or two days. 



Since the results obtaine<l in serum diagnosis may be intluenced by previous 

 subcutaneous malleinization, horses from which blood is obtained for this purpose 

 must not be tested with mallein until after the withdrawal of the serum. 



1. Complement Fixation Method. The method of Bordet 

 & Gengou, inaugurated in 1901, and adapted by Wasserman & 

 Bruck for the practical diagnosis of syphilis in particular, is 

 based upon the demonstration of antibodies in the blood serum. 

 These antibodies, with the aid of their antigen, have the power 

 of fixing the complements of fresh serum and thus divert them 

 from hemolytic systems. This method which was worked out 

 by Schiitz & Schubert for the diagnosis of glanders has already 

 given results of such an exact nature that it may be looked upon, 

 at this time, as the best sero-diagnostic method for the de- 

 termination of this disease. 



If an experiment animal is repeatedly treated with red blood 

 corpuscles from another species, the serum of the former develops the 

 property of dissolving* the red blood corpuscles of the latter within 

 a short time, even in very dilute solution. By heating for 30 minutes 

 at 56° to 58° C. this property is destroyed. However, if fresh serum 

 from any animal, not previously treated as above described, is added 

 to a mixture of serum thus incubated (inactivated) plus red corpuscles, 

 a solution of the erythrocytes (hemolysis) again takes place. This 

 phenomenon therefore occurs as the result of the action of two sub- 

 stances: (1) A thermostabile substance which is found only in the 

 serum of an animal previously treated with the blood corpuscles from 

 another species, and which develops as a reaction product, or antibody 

 for red blood corpuscles, i. e., as an antigen. (2) A thermolabile sub- 

 stance which is present in the fresh serum of any animal and which 

 is designated as complement or alexin. According to Ehrlich's theory 

 this process may be explained by supposing that an antibody possesses 

 two afiinities or haptophore groups (see p. 447) (hence the name: 

 hemol.vtic amboceptor or mediating body) ; one of these combines with 

 the red blood corpuscles as antigen, the other with the complement. 

 The complement can not combine directly with the antigen, but if 

 anchored to it by means of the amboceptor it will act as a sort of 

 digestive or proteolytic ferment and dissolve the red blood corpuscles. 

 (According to Bordet 's theory the red corpuscles are sensitized for 

 the alexin by the antibody in a manner similar to the action of mordants 

 in the dyeing of cloth, for which reason he designates the antibody as 



*NOTE: — Strictly speaking there is no complete solution of the red blood corpuscles but 

 only an action of the hemolysin on their stroma which permits the escape of the hemoglobin. 



