148 INFECTION AND RESISTANCE 



development of immime-isolysins. Work on other species of animals 

 has indicated that this fact has a broad significance and that similar 

 differences between individuals of the same species occur in many, 

 if not all, species of animals. Isolysins similar in principle to those 

 of Ehrlich and Morgenroth were produced by Ascoli 27 in rab- 

 bits; by Todd and White, 28 in oxen; by Ottenberg, Kaliski, and 

 Friedmann 29 in dogs ; by Ottenberg and Thalhimer 30 in cats, and by 

 Hada and Rosenthal 31 in chickens. In all these instances the iso- 

 lysins developed showed the same peculiarities, namely, that they 

 attacked the cells of certain individuals and left the cells of other 

 individuals of the same species unharmed. Recent work on the 

 isolysins occurring naturally in the human blood has thrown con- 

 siderable light on the nature of immune isolysins. 



The occurrence of isolysins in human blood was first noted by 

 Maragliano 32 in 1892, and a large amount of work had been done 

 before it w r as clear that the occurrence of isolysins is not a charac- 

 teristic of disease. The work of ]\Ioss 33 and of Grafe and Graham 34 

 has shown that the occurrence of isolysins is parallel with that of 

 iso-agglutinins (see chapter on agglutination), and that there are in 

 human bloods two isohemolysmogens, A and B (corresponding to the 

 two agghitinogens, A and B), and two isohemolysins, a and/3. The 

 hemolysinogens occur regularly according to the same rule as the 

 agglutinogens, but the hemolysins, while they always follow the 

 same rule when present, may be present or latent. Thus a person 

 whose red cells contain A may or may not have ft , and never has a; 

 a person whose red cells contain B may or may not have a, but can 

 never have /?; a person whose red cells are susceptible to both a and 

 ft never has any hemolysin in the serum. It seems likely that the 

 substances A and B, which cause the susceptibility of red cells to 

 the corresponding hemolysins, are definite biochemical structures 

 which possibly may be inherited in a similar way to the iso-agglu- 

 tinogens and that similar substances (probably a larger number of 

 them) are present in the blood cells of various species of lower ani- 

 mals. This readily explains the apparent irregularity attending the 

 development of isolysins in the lower animals. The reason for the 

 natural occurrence of such isolysins in human sera and occasionally 

 in the sera of lower animals, however, is a complete mystery. From 



27 Ascoli. Miinch. med, Woch., 1901. 



28 Todd and White. Nature. June 23, 1910. 



29 Ottenbersr, Kaliski, and Friedmann. Jour. Med. Res., Vol. 28, 1913. 



30 Unpublished personal communication. 



31 Hada and Rosenthal. Zts. f. Imm., 1913, 16. p. 524. 



32 Maragliano. "IX Kongr. f. Innere Med.." 1892. 



33 Moss. Johns Hop. Hosp. Med. Bull, March, 1910. 



34 Grafe and Graham. Munch, med. Woch., 1911, pp. 2257, 2338. 



