CHAPTER LXVIII 



THE HUMAN BLOOD GROUPS' 



K. LANDSTEINER 



Rockefeller Institute for Medical Research, New York City 



ISOAGGLUTININS AND ISOAGGLUTINOGENS 



After it was established that serological methods can be used for the detection of 

 species differences of animal cells and proteins as well as for differentiating micro- 

 organisms, the question presented itself whether the same principle is applicable to 

 the detection of individual variations within a species. The first experiments along 

 this line were made with human blood by mixing erythrocytes with serum of other 

 healthy individuals.^ Since it was generally accepted that serum of the same species 

 is the most innocuous medium for cells one would have expected to find either no 

 changes at all or else a great varie<^y of reactions of rather small order. In fact, the 

 tests yielded entirely negative results in certain combinations while in others an ag- 

 glutination of the red cells took place which was not less pronounced than that 

 brought about by the action of serum on the blood of a foreign species. 



Using another method soon afterwards, Ehrlich and Morgenroth^ demonstrated 

 antibodies in the serum against cells of the same species — isoantibodies — after inject- 

 ing goats with the blood of other goats. The further study of the isoagglutination of 

 human blood reyealed an unexpected feature of these phenomena. The reactions do 

 not occur at random but follow a definite rule. With regard to isoagglutination all 

 individuals can be divided almost without exception into four well-defined groups, 

 three of which were described by the writer,^ the fourth, of rarer occurrence, by 

 von Decastello and Sturli.^ The blood-group characteristics were found to be consti- 

 tutional and to remain unchanged throughout life; the agglutinogens are inherited 

 according to the Mendelian laws (von Dungern and Hirschfeld, Ottenberg). A simple 

 explanation of the reactions can be given by assuming the existence of two agglutino- 

 gens A and B in the cells and two agglutinins a (or anti-A) and /3 (or anti-B) in the 

 sera. 



For the designation of the blood groups necessary for practical purposes numbers 

 have been generally used. Considerable confusion, however, and even accidents, were 

 caused by the existence of two different arbitrary numberings, namely, the classifica- 



' For a detailed review of the subject cf. Hirszfeld, L.: Ergcbn. d. Hyg., 8, 367. 1926; Levine, P.: 

 Ergebn. d. inn. Med. u. Kinderh., 34 (in press); Schiff, F.: Die Technik der Bliitgnippennniersiichung. 

 Berlin: Springer, 1926; Doan, C. A.: Physiol. Rev., 7, i. 1927; Snyder, L. H.: Arch. Path. 6" Lab. Med., 

 4,215. 1927; Lattes, L.: Die Individnalitdt des Bluies. Berlin: Springer, 1925. 



" Landsteiner, K.: Centralbl. f. Baldcriol., 27, 357. 1900. 



5 Ehrlich, P., and Morgenroth, J.: Bed. klin. Wchnschr., 37, 453. 1900. 



^ Landsteiner, K.: Wien. klin. Wchnschr., 14, 1132. 1901. 



s von Decastello, A., and Sturli, A.: Mtinchen. med. Wchnschr., 49, 1090. 190a. 



89a 



