376 IMMUNOLOGY 



possess a species-specific human protein in common, but there are 

 two haptens, ''A" and "B," which make possible these four types. 

 One type is represented by the species-specific protein not associ- 

 ated with either hapten, this is type "0." A second type exists be- 

 cause of the presence of hapten "A," a third because of hapten 

 "B," and a fourth has both "A" and "B" associated with the 

 species-specific protein. It is interesting to note that haptens may 

 be carbohydrate-lipoid complexes, as, for example, the ''A" and 

 "B" factors of red cells or the hapten fraction of Forsmann's 

 antigen or perhaps just lipoids as suggested by Eagle for 

 the antigen used in the Wassermann reaction. They may be pure 

 carbohydrates such as one finds as partial antigens representing 

 many bacterial types within a species as well as characterizing 

 some species; or the hapten may be some chemical group such 

 as tartaric acid, etc., attached to a protein. 



Hapten May Dominate a Serological Reaction. — Most haptens 

 are incapable of stimulating antibody formation when separated 

 from the protein fraction and injected into the animals. Anti- 

 bodies formed as a result of injecting the hapten-protein complex 

 can react with either the hapten alone or the hapten-protein com- 

 bination. It seems that the hapten dominates the picture to the 

 extent that one may not observe the presence of antibodies for 

 the species-specific protein part of the antigen in immune serum 

 which theoretically should contain them. 



Suppression Phenomenon of Landsteiner. — In connection with 

 haptens the "suppression phenomenon" of Landsteiner is of in- 

 terest. This is illustrated by the work of Wormall. He iodized 

 a protein that contained tyrosine and then prepared a good pre- 

 cipitating antiserum for the iodized protein. He found that when 

 he added diiodotyrosine to tubes containing the iodized antigen 

 and its antiserum, the specific precipitate did not form, it was sup- 

 pressed. 



Arsanilic Acid Coupled to Histidine and Tyrosine by Hooker 

 AND Boyd. — By means of this plienomenon Hooker and Boyd were 

 able to prove that the arsanilic acid which they linked to gelatin 

 couples to histidine, and when linked to egg white it couples with 

 both tyrosine and histidine. They prepared good precipitating 

 antisera for the arsanilic acid gelatin and egg white antigens re- 

 spectivel}'. They then sj'uthesized tyrosine-like ar.sanilic acid and 



