34 IMMUNO-CATALYSIS 



or a much larger number of flagella. Fifty ml. of serum (estimated con- 

 servatively by Topley) obtainable from the 2760 g. rabbit would yield 

 2.5X10^ units of agglutinin, resulting from the stimulus of S.BXlO^'* 

 antigen molecules, and capable of flocking 5X10^^ bacteria. In other 

 w^ords, one molecule of antigenic substance gives rise to an amount of 

 circulating agglutinin capable of flocking 600 bacteria. As they state, 

 this evaluation does not take into account the large reservoir of anti- 

 body in tissue fluids and cells which by repeated daily bleeding would 

 contribute in no small measure to a magnification of this figure. 



Studies by Heidelberger and Kendall (1930), and Heidelberger, 

 Kendall and Soo Hoo (1933) likewise demonstrated the striking dis- 

 proportionality between an artificial antigen and the amount of anti- 

 body produced. The antigenic substance was colored R-salt-azo- 

 benzidine-azo-crystalline egg albumin. The injections of the antigen 

 were carried out either in solution, or adsorbed on collodion or alum 

 particles. Fifty ml. of a suspension of antigen adsorbed on collodion, 

 the amount used for 16 injections, contained 0.55 mg. of dye and 140 

 mg. of collodion. In all but one series the injections were given intra- 

 venously, four daily injections each week for four weeks; many animals 

 were given an additional course of two, three or four weeks. 



Quantitative data showed that as much as 0.73 to 0.94 mg. of cir- 

 culating antibody per ml. of serum may be formed in response to in- 

 jections of antigen totaling 0.35 to 0.55 mg., or a total response for 

 the rabbit of over 100 mg. of circulating antibody for every milligram 

 of antigen injected. Since the ratio of antigen to antibody in the pre- 

 cipitate has been found to average 1 : 7 at the equilibrium point, the 

 authors stated that at least 12 times as much antibody as necessary to 

 combine with the amount of antigen used is formed. This evaluation, 

 of course, does not take into account the antibodies present in the 

 tissues as well. 



Morgan (1937) extracted an antigenic material from B. dysenteriae 

 (Shiga) by diethyleneglycol. This material contained a polysac- 

 charide, gave positive biuret and negative ninhydrin reactions. On 

 immunizing a horse with a total of 16.2 mg. of material the production 

 of 1.64 mg. of antibody protein per ml. of blood serum was attained. 

 Morgan assumes a blood serum volume of 25 liters obtainable from 

 the immunized horse, or a total of 41 g. of antibody protein in re- 

 sponse to 0.0162 g. of antigenic material, a ratio of (41/0.0162) 



