206 CHEMISTRY OF THE nniUXITY KEACTIOXS 



The mechanism of the reaction is not understood. Jobling and 

 Petersen have suggested that the antigen-antibody combination may 

 adsorb or bind the antipro teases of the serum, so that the normal pro- 

 tease digests the serum proteins. Or it may be that union of antigen 

 and antibody activates the complement, or binds it to the antibody so 

 that it digests either the antibody or other proteins of the seinim. 

 It also is suggested that enzymes are set free from the tissues injured 

 by the specific protein, or by disease, which digest the foreign protein 

 or the cellular joroteins that maj' have escaped from the tissues into the 

 blood stream. 



The reaction possesses a certain specificity, but just the degree of 

 this specificity has not been agreed upon. The claim of Abder- 

 halden ^^^ and his followers, that it is by far the most specific of im- 

 munity reactions, whereby disintegrati'^n of small amounts of any 

 given organ of an individual can be determined by specific reactions- 

 between his serum and that organ, with such refinement that even 

 cerebral localization is possible, is scarcely credible. There are so 

 many possible sources of error in the original technic that even with 

 great care the charge of incorrect results fi-om incorrect technic cannot 

 be escaped, and therefore, those who do not accept the doctrine of its 

 specificity are always on the defensive. Nevertheless, so many careful 

 and experienced investigators have found the original Abderhalden 

 reaction to give at times absolutely non-specific and hopelessly para- 

 doxical results, that its diagnostic value for either clinical or scientific 

 purposes must be considered at present as unproved,''^^ whatever the 

 final decision as to its standing as a specific reaction may be. 



Serum treated with various inert, finely divided particles, such as 

 kaolin, starch, silicates, etc., may acquire the property of giving posi- 

 tive reactions. This is another point of resemblance to anaphylatoxin 

 foraiation, and against the specificity of the reaction, indicating that 

 the antigen merely acts as a' non-specific adsorbent. 



By far the most satisfactory results have been recorded in the 

 diagnosis of pregnancy by means of placental antigen. This may be 

 explained by the fact that the protease activity of the serum seems to be 



39e A reply to numerous criticisms is given by Abderhalden, Fermentforscliung, 

 1916 (1), 351; this and other numbers of this journal also consist lavjroly of 

 articles on the Abderlialden reaction. 



39tO. J. Elsesser (Jour. Infect. Dis.. mifi (19), 055), wirking in my labora- 

 tory with the purified vegetable proteins of Osborne, foimd tlnit at the best tlie 

 specificity of the reaction was less than that of tlie anaplivlaxis reactioji, and 

 there were many absolut<']y non-specific and irrational reactions. As tliese j)ure 

 proteins furnish a much more appropriate material for studying specificity tlian 

 the tissues or sera commonly used, it would seem (liat the results thus obtaiiied 

 are excellent prof)f of tlie uncertainty and unreliability of the reaction. Careful 

 quantitative studies of tlie setting free of amino-acids by serum incul)ated with 

 placenta, liy Van Slyke and his a^-^sociates, also showed a c()m))letc lack of spe- 

 cific proteolysis by pregnancy scrum (Arcli. Int. ^led., 1017 (10), 5fl; Jour. 

 Biol. Chem.,"l915 (23), 377: see also Hulton. ibid., 1010 (25), 103). 



