56 IMMUNO-CATALYSIS 



specific function of the tissue cells of the host, meaning the specific 

 function which is operative in active immunity. 



The rate at which the passively introduced anti-pneumococcal rabbit 

 antibody disappears in the body of the rabbit shows that 37. 6 per cent 

 was eliminated during 22 Vi hours, and 55 per cent during 48 hours. In 

 contrast, the foreign proteins (or polysaccharides) administered to a 

 host for immunization or for therapeutic reasons persist for a decidedly 

 longer period of time. As will be discussed below, production of an 

 antibody can occur within four to 10 hours after the injection of an 

 antigenic material. It is therefore reasonable to assume that the length 

 of the period, during which a species specific protein can persist in a 

 host of the same species, appears to be long enough to exercise an 

 antigenic stimulus. The absence of such a stimulus would emphasize 

 the importance of the difference of molecular structure of the foreign 

 antigenic substances from those of the host as the most critical differ- 

 ence in the stimulation of an immune response. 



In contradiction to the observation of Heidelberger, et al., Kooyman 

 and Campbell (1948) reported that antibody globulin introduced 

 passively into rabbits can enter into the dynamic equilibrium state of 

 the body without loss of antibody properties. Experiments were carried 

 out by injecting C^^ labeled dl-leucine into a rabbit which was actively 

 immunized against p-azophenylarsonic acid-ovalbumin. Ten days after 

 the last injection, an injection of 10 ml. of concentrated rabbit pneu- 

 mococcus antiserum (Type I) was given intravenously, followed by a 

 similar injection next day. On the same day, an injection of 30 ml. of 

 a one per cent leucine solution was given intraperitoneally. The leucine 

 contained C^^ in the carboxyl group. Similar injections of leucine were 

 given on the three following days, 1.15 g. of leucine being injected in 

 all. Samples of serum were taken on 5, 9, and 16 days after. The anti- 

 bodies were precipitated with corresponding antigens, washed with 

 saline three times, once with distilled water, twice with alcohol and 

 ether, and analyzed for C^^ after drying. These materials were reported 

 to contain labeled carbon. 



If interpreted to indicate that passively introduced antibody globulin 

 is digested to the stage of amino acids and peptides and the C^* con- 

 taining antibody globulin is resynthesized in the absence of the specific 

 antigen, these findings would be contrary to the facts underlying the 

 concept of the mechanism of antibody formation, namely, that antibody 



