MECHANISM OF ANTIBODY FORMATION 61 



strate the presence of homologous antibody was interpreted (Fehon, 

 1949) to be due to so firm an attachment of the antigen to cell sub- 

 stances that it is no longer free to act as an antigen. If we accept the 

 idea that antigen functions as a catalyst, the above interpretation of 

 "immunological paralysis" would be in agreement with the fact that a 

 catalyst which irreversibly combines with a component of a reaction 

 system would be incapable of catalyzing the specific process. 



The fact that these antigenic polysaccharides persist in the circula- 

 tion for long periods and are excreted through the kidney unchanged 

 fails to indicate a relationship between these results and an in vitro 

 observation by Dubos and MacLeod (1938) that pneumococci are very 

 rapidly rendered non-antigenic (in regard to type-specific antibody) 

 by leucocyte extracts. 



2. An Inquiry into the Nature of Factors Controlling 

 the Balance of Antigen and Antibody During Immuni- 

 zation 



For an understanding of the theories advanced concerning the mech- 

 anism of the formation of antibodies it may be of interest to consider 

 the possible factors which influence the rate of antibody production, its 

 decline, and also the length of the period during which an antigen may 

 remain in the host system. The amount of antibody formed in response 

 to antigenic stimuli will be dependent on the rate at which antibody is 

 removed, or dissociates from the site of its synthesis into the humoral 

 systems. With the accumulation of antibody in the humoral system 

 and tissues an equilibrium condition will be established.* The attain- 

 ment of this final state of equilibrium may represent the peak of anti- 

 body concentration. The maintenance of the peak of antibody concen- 

 tration would be dependent on several factors. The rate at which 



*The question of how soon the above reaction equilibria can be set up in vivo may 

 best be answered by a consideration of the following observations. Two hours after 

 subcutaneous injection, egg-white was demonstrated in the urine and blood by the 

 precipitin reaction (Ascoli, 1902; Obermayer and Pick, 1902). According to Dochez 

 and Avery (1917), if rabbits are infected intraperitoneally with pneumococcus a 

 substance specifically precipitable with antipneumococcus serum can be demonstrated 

 in their blood stream, freed from bacteria by filtration, from within two to six hours 

 following the time of infection. One may find other similar observations in the 

 literature. These facts show how rapidly the antigenic material finds its way into 

 the circulation introduced through various routes. 



