56 INTRODUCTION TO IMMUNOCHEMICAL SPECIFICITY 



1937) to attempt to demonstrate A and B in mummified human 

 remains. The attempt seemed to be successful. These workers tested 

 more than 300 specimens, mostly from Egypt in the Old World and 

 from Mexico and Peru in the New World. The technique, though 

 exacting and at times even exasperating, was simple in theory ; pul- 

 verized dried tissue (usually muscle) was mixed with carefully 

 titrated anti-A and anti-B agglutinins and the mixture tested after 

 a suitable interval for evidence of removal of one or more of the 

 agglutinins. Removal of anti-B was considered to indicate the pres- 

 ence in the tissue of the B antigen, removal of anti-A the presence 

 of A. Removal of neither suggested either that the specimen came 

 from an individual of group O or that any antigens originally present 

 had deteriorated. Removal of both anti-A and anti-B suggested group 

 AB or nonspecific destruction or removal of agglutinins or anti- 

 bodies in general. 



The results obtained were on the whole in line with the present 

 distribution of the A and B antigens in human races, confirming 

 the antiquity of the ABO blood group system. (Some authors had 

 suggested, amazingly, that the A and B genes were of recent origin.) 

 The B antigen was apparently found in pre-Columbian specimens 

 from Mexico (Taylor and Boyd, 1943), a finding which, if ever 

 confirmed, might support the suggestion, made on other grounds, 

 that the B gene was eliminated in the aboriginal inhabitants of 

 America by natural selection (Boyd, 1959). This subject has been 

 reviewed by Smith (1960). 



Origin of Isoagglutinins Anti-A and Anti-B 



The presence of anti-A and anti-B in normal human plasma seems 

 at first glance to be an exception to the rule that antibodies to blood 

 group antigens do not usually appear without some history of un- 

 usual antigenic stimulus. The exception is a marked one, for the 

 occurrence of these isoagglutinins is very regular. When anti-A 

 or anti-B, if expected according to Landsteiner's rule, are absent, 

 there is usually a special explanation, as Race and Sanger point out. 

 It is natural to ask why these agglutinins appear with such regularity. 

 There have been two main theories. 



According to one theory, the isoagglutinins anti-A and anti-B are a 

 result of the action of the ABO genes just as the ABH antigens are. 



