AGGLUTININS AND PRECIPITINS 99 



Iso-hemagglutinins, Classification. Iso-hemagglutinins are 

 those which exist in certain members of a species for cells of cer- 

 tain other members of the same species. Although iso-hemagglu- 

 tinins may somewhat rarely occur in lower animals, they appear 

 with great regularity in human blood. They were discovered in 

 1906 by Landsteiner and Shattock, working independently. 

 Landsteiner, by a study of the interaction of sera and corpuscles, 

 classified all human bloods in three groups and determined that the 

 property of iso-agglutinination is normal to man and does not vary 

 under pathological conditions. Hektoen noted in 1907 that the three 

 groups do not include all individuals, and in the same year Jansky 

 published the classification in four groups. This was confirmed by 

 Hektoen and subsequently adopted by Ottenberg. Moss, in 1910, 

 without knowledge of Jansky's work, also found that it is necessary 

 to divide bloods into four groups in order to include all individuals, 

 but unfortunately employed a system of numbering the groups the 

 opposite of that of Jansky. Because of the priority of Jansky's sys- 

 tem and its important support by Hektoen and by Ottenberg and 

 others, we prefer to use it rather than that of Moss. Groups I and 

 IV are transposed in the two systems but Groups II and III re- 

 main the same, hence, groups are transposable from one basis to the 

 other. The groups are not present at birth, but become established at 

 about the end of the first year of life and remain constant thereafter ; they 

 are heritable according to the Mendelian law. Disease does not change 

 the group of an individual, although, according to some of our experi- 

 ments, it seems possible that the agglutinin titer may be somewhat 

 reduced by prolonged disease. Jansky included in Group I those 

 bloods whose sera agglutinate cells of all other groups and whose 

 cells are not agglutinated by any sera; Group IV is the reciprocal 

 of Group I in that the sera agglutinate no cells, but the cells are 

 agglutinated by sera of all the other groups. Groups II and III are 

 reciprocals of each other and occupy intermediate positions between 

 Groups I and IV. This may be rendered clearer by the following table : 



Group I. Serum agglutinates cells II, III and IV. 



Cells agglutinated by no sera. 

 Group II. Serum agglutinates cells III and IV. 



Cells agglutinated by sera I and III. 

 Group III. Serum agglutinates cells II and IV. 



Cells agglutinated by sera I and II. 

 Group IV. Serum agglutinates no cells. 



Cells agglutinated by sera I, II and III. 



The following chart presents the classification graphically; the 

 -f- sign indicates agglutination : 



JANSKY CLASSIFICATION 



Sera 



I. II. III. IV. 

 j 



^ II. + - + - 



3 in. + 



iv. + + + - 



