MECHANISM OF ANTIBODY FORMATION 105 



determinant group of tKe antigen or a serologically related group in 

 the repective antibody molecules. The concept of the identity of 

 antigen and antibody postulated by Jordan must be rejected also for 

 genetic reasons, and for reasons that an antigen is antigenic by 

 virtue of being species specifically unrelated to the antibody globulin 

 elaborated by the immunized host. 



Jordan (1944) assumes that antibody formation does not take place 

 during a period of from six to 48 hours following the injection of anti- 

 gen. This assumption is to be denied for it has been observed (Ham- 

 burger, 1902; Oerskov and Anderson, 1938; Ramon, 1928, etc.) that 

 the production of antibody can be demonstrated three to four hours 

 after the injection of antigen. On the basis of this assumption Jordan 

 postulates that antigens initially produce only small amounts of anti- 

 bodies, and that the subsequent increase in the amount of antibody 

 results from an autocatalytic process mediated by the antibody mole- 

 cule itself. As stated above, a measurable amount of antibody has been 

 demonstrated a few hours after the injection of antigen. There is no 

 doubt that non-measurable amounts of antibody must have been 

 synthesized at a still earlier period, indicating a rapid output of anti- 

 body by a process which, in our opinion, is possible if antigen func- 

 tions as a catalyst. 



The autocatalytic concept of Jordan implies that the antibody pro- 

 duction should be a continuous process. A second implication of Jordan's 

 concept is that the introduction of an antibody obtained from an 

 actively immunized animal into another animal of the same species 

 should autocatalytically produce new antibody in amounts many-fold 

 greater than the amount introduced. The production of antibody 

 postulated in this manner in a normal individual would be comparable 

 to the production of an infection in a host by an infectious agent de- 

 rived from a disease bearing host. Jordan considers this possibility in 

 the above described manner, but was unable to cite a single experi- 

 mental observation. As is well known, passive immunizations are of very 

 short duration, and the experiments of Heidelberger, Schoenheimer 

 and their associates (1942), as discussed in a preceding section, have 

 shown that an antibody derived from a rabbit and introduced into 

 a normal rabbit enters into metabolic reactions resulting in its 

 disappearance. 



