Ontogeny of Immunological Properties 



557 



that the maximum amount of impurity that 

 might be present in a particuhir pi-eparation 

 and still be physicochemically undetected is 

 sufficient to induce the formation of the 

 cross-reacting antibodies that are obtained 



Fig. 205. Electrophoretic patterns of highly puri- 

 fied conalbumin (A) and of six times recrystallized 

 ovalbumin (B and C) (from Cohn, Wetter and 

 Deutsch, '49). 



upon immunization. No clear-cut demonstra- 

 tion of this has been made in studies of cross- 

 reactions as far as the present author is 

 aware. For this purpose it would presumably 

 be necessary to run parallel immvmizations 



portant to test for possible competition of 

 antigens and for adjuvant action. In experi- 

 ments by Vaughan and Kabat ('53), showing 

 the presence of cross-reacting antibodies after 

 immunization with minimal amounts of 

 highly purified ovalbumin, the quantities of 

 impurities that might be present would not 

 have been presumed to induce antibody for- 

 mation. However, they interpret their results 

 as due to trace contaminants in their oval- 

 bumin antigen. 



Another way of interpreting cross-reactions 

 is on the basis of similar determinant, or 

 combining, groups on chemically different 

 proteins or other antigenic substances. This 

 can best be illustrated by the fundamental 

 experiments of Landsteiner ('17-'46) in which 

 proteins are coupled with small molecular, 

 chemically well defined substances. Thus 

 horse serum protein can be coupled with 

 diazotized arsanilic acid (Atoxyl) as illus- 

 trated in Figure 206, the union being pre- 

 sumably with certain amino acids of the 

 protein that have benzene or heterocyclic 

 rings, such as tyrosine, histidine or trypto- 

 phane. When this is injected into a rabbit 

 the antiserum that is obtained is found to 

 react not only with the immunizing antigen 

 but also with other proteins, such as chicken 

 serum protein, that have been similarly 

 coupled with diazotized Atoxyl. On the other 

 hand it will not precipitate chicken serum 



HjOjAs 



"-I ' 



i 



I Diazotized Arsamlic Acid 



Diazotized Arsanilic Acid ^ 



Fig. 206. Illustration of the manner in which a hapten may be coupled with a protein 



with the maximum possible amounts of the 

 suspected impurities and determine whether 

 or not the amounts of antibody produced 

 corresponded to those indicated by the cross- 

 reactions. At the same time it would be im- 



protein that has been coupled with other 

 simple substances, such as diazotized sul- 

 fanilic acid. The chemically introduced 

 group is, then, a determinant of specificity. 

 It is also termed a hapten. A simple hapten 



