CHAPTER X 

 ISOHEMAGGLUTININS— BLOOD GROUPS 



Isohemagglutinins. — Discovery. — The first recorded observation 

 that the serum of a normal, healthy individual can bring about 

 agglutination of the red cells of other normal individuals of the 

 same species was made by Landsteiner in 1900. This preliminary 

 report M^as followed by an intensive study of the sera and red 

 cells of twenty-two individuals. From an analysis of the data ob- 

 tained in this study, Landsteiner (1901) discovered that three 

 definite blood groups were represented. The following year De- 

 Castello and Sturli (1902) continued this work at the suggestion 

 of Landsteiner. They not only confirmed the existence of the 

 three groups, but found four exceptions which are the first re- 

 corded examples of the fourth group. The}^ even discussed four 

 possible groups which they designated hy numbers rather than by 

 letters. Since the four exceptions tliat constituted a new blood 

 group were bloods from young children, DeCastello and Sturli 

 thought that they might be members of one of Landsteiner 's 

 groups that had not yet acquired their full quota of necessary fac- 

 tors. According to Ottenberg (1928) and also Zinsser and Coca 

 (1931), Landsteiner immediately appreciated the existence of the 

 four groups. He had previously postulated (1901) two agglutinins 

 and two agglutinogens as was later done by Jansky (1907). 

 Hektoen (1907) and Gay (1907) both confirmed the existence of 

 the three human blood groups described by Landsteiner. Two 

 years later Landsteiner (1909) published a more complete discus- 

 sion of his work on isohemagglutinins. In 1910, Moss offered a 

 classification of tlie 1)1 ood groups which has found wide acceptance. 

 Apparently Hektoen (1907), Gay (1907) and Moss (1910) were 

 not aware that previous workers (Landsteiner, et al.) had con- 

 sidered more than three groups and had postulated two agglutinins 

 and two agglutinogens since both Hektoen and Moss speak only of 

 Landsteiner 's three groups and certain exceptions and both as- 

 sume the existence of three agglutinins. Landsteiner (1928), 

 Ottenberg (1928) and Snyder (1929) have reviewed the literature 



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