ANTIBODIES I 



As an example, let us take the aromatic amine, metanilic acid, 

 and diazotize the amino group by treating the compound with nitrous 

 acid (Fig. 1-5). 



HNO.. -^ 



JSO3H I JSO.,H 



Metanilic acid- H CI Diazotized metanilic 



acid 



Fig. 1-5. Diazotization of metanilic acid. 



The resulting diazonium salt will couple with phenols in alkaline 

 solution to give colored azo dyes (Fig. 1-6). It will also couple with 

 the phenolic group of the amino acid tyrosine, a constituent of most 

 proteins. 



+ 

 JSO3H H 



Diazotized metanilic Phloroglucinol Azo dye 



acid 



Fig. 1-6. Coupling of diazotized metanilic acid with phloroglucinol to form 

 an azo dye. 



Let us suppose we couple the diazotized metanilic acid (our hapten) 

 with the mixture of proteins provided by horse serum. If we repre- 

 sent the horse serum proteins by H and the diazotized metanilic acid 

 by M, we may reprsent the coupled azoprotein as HM. Injection of 

 this compound HM into rabbits will usually cause the production of 

 a number of different antibodies to the proteins of horse serum, which 

 we may designate collectively as anti-H, and antibodies to metanilic 

 acid, which we may designate as anti-M. 



If, on testing the rabbit antibodies with the antigen HM we in- 

 jected, we get a positive serological reaction (formation of a specific 

 precipitate), we shall not know whether this is due to the union of 



