252 FERMENTS AND ANTIFERMENTS 



ABDERHALDEN'S SERODIAGNOSIS OF PREGNANCY* 

 Principles. As previously stated, this test aims to discover in the 

 blood-serum of pregnant women, the presence of a proteolytic ferment 

 capable of splitting coagulated placenta or placental peptone into simple 

 substances, such as amino-acids. The presence of this ferment indi- 

 cates that its antigen is present, i. e., the woman is pregnant, and syn- 

 cytial cells or their products have gained access to the maternal circu- 

 lation with the result that a protective ferment has been produced. 

 According to Abderhalden, while this ferment is not absolutely specific 

 for the placenta of the same species, it is incapable of cleaving any other 

 protein. For example, the serum of a pregnant cow contains a ferment 

 capable of splitting the protein of human placenta, but does this less 

 satisfactorily than does the ferment in human serum. The ferment of 

 pregnancy, however, will not split the protein of cancer-cells or of nor- 

 mal tissues. 



Although all investigators are in accord regarding the presence of a 

 proteolytic ferment in the blood-serum of pregnancy, the specificity of 

 the ferment has been questioned. To all such queries Abderhalden 

 has usually replied by calling attention to errors in technic, and, indeed, 

 while the dialysis method is easy of manipulation, opportunities for 

 technical error are so numerous that the test is far from simple. 



Methods. Two methods have been devised by Abderhalden for 

 the demonstration of the protective ferments in the blood-serum of 

 pregnancy: 



1. The Dialyzation Method. Specially prepared and coagulated 

 placenta and fresh serum are placed in a dialyzing capsule so prepared 

 that it will permit the passage of peptones and amino-acids only. The 

 filled capsule is placed in sterile distilled water, and incubated for from 

 sixteen to twenty-four hours, when the dialysate is tested by the biuret 

 or ninhydrin test for peptones and amino-acids. Under proper condi- 

 tions the presence of these substances indicates that the placental tis- 

 sue has been digested by a ferment in the serum, and, if this ferment 

 is specific for placental cells, this indicates that the serum tested is from a 

 pregnant woman. This is the method usually employed. 



2. The Optical Method. This method is based upon the same prin- 

 ciple as the dialyzation method. Into the tube of a polariscope place a 

 solution of placental peptone and the serum to be tested. Warm the 



Abderhalden: Abwehrfermente des tierischen Organisims, Julius Springer, 

 third edition, 1913. 



