170 IMMUNOLOGY 



described by DeCastello and Stiirli (1902) failed to agglutinate 

 the cells of any group while the corresponding red cells were 

 agglutinated by the sera of each of the three Landsteiner groups. 



Mechanism Postulated by Landsteiner. — To explain these phe- 

 nomena, Landsteiner (1901, 1928) says that he and later Jansky 

 (1907) postulated the existence of two agglutinins, alpha and 

 beta, and two corresponding agglutinogens, A and B. He fur- 

 thermore assumed that there exists a reciprocal relationship be- 

 tween them; i.e., when an agglutinogen is absent from the red 

 cells of an individual the corresponding agglutinin will be pres- 

 ent in the serum, and, conversely, when an agglutinogen is present 

 in the red cells, the corresponding agglutinin will be absent from 

 the serum. This explains why the red cells are not agglutinated 

 by the homologoiLs serum. 



Thus, for group where the red cells contain neither agglu- 

 tinogen, the corresponding serum contains both agglutinins alpha 

 and beta. In group A, the red cells contain agglutinogen A, and 

 hence group A sera will contain only beta agglutinin. Likewise, 

 group B sera will contain only alpha agglutinin and group AB 

 neither agglutinin. 



This will be better appreciated from an inspection of Table 



II. 



Table II 



Fig. 6 illustrates the phenomena observed from mixing the cells 

 and sera of the four types. 



Moss's Classification in General Use. — Kennedy (1929) states 

 that the classification suggested by Moss (1910) is used in 78 

 per cent of the hospitals of America. This is interesting in view 

 of the fact that in 1921 a committee representing the American 

 Association of Immunologists, the Association of Pathologists and 

 Bacteriologists, and the Society of American Bacteriologists recom- 

 mended the adoption of the Jansky classification. This was done 



