970 ANAPHYLAXIS AND ANAPHYLACTOID REACTIONS 



The antigen may be spoken of as "anaphylactogen" and the antibody as "anaphylac- 

 tin," There is no doubt that the anaphylactogen is of protein nature, but there re- 

 main the questions as to how simple the protein fractions may be and still be antigenic 

 and whether or not non-protein substances may be antigenic. 



Whole proteins are not necessarily anaphylactogenic, and even if so there may be 

 certain amazing variations. According to Wells, the proteins which may be spoken of 

 chemically as incomplete, containing a small number of amino acids, are non-anti- 

 genic. This is true of protamines and histones and the nucleoproteins and hemo- 

 globins, Starin'^ has shown that gelatin, which contains neither tryptophane nor 

 tyrosine and little phenylalanine, is not antigenic. Wells and Osborne^ have shown 

 that zein, gliadin, and hordein, poor in diamino acids, are definitely antigenic, whereas 

 protamines, rich in diamino acids, are not antigenic. Wells concludes that lysine and 

 presumably glycine and tryptophane are of no significance, but that "since no protein 

 is known which does not contain either histidine or arginine," nothing can be said 

 definitely about these bodies. According to experiments of TenBroeck,^ racemized 

 proteins, which are not attacked by proteolytic enzymes, do not act as anaphylacto- 

 gens. Gay and Adler" state that the euglobins contain the sensitizing but not the 

 intoxicating substance, but Kato^ maintains that they contain both. After hydrolysis 

 of coagulated egg white with steam under pressure. Fink* found that fractions precipi- 

 tated by three-fourths and complete saturation with ammonium sulphate were slight- 

 ly anaphylactogenic and definitely antigenic otherwise. In spite of his controls it is at 

 least possible, especially since the other fractions thrown down with a smaller concen- 

 tration of ammonium sulphate were non-antigenic, that the reactions were anaphylac- 

 toid. The difficulty of interpretation of non-fatal results is becoming more widely 

 recognized, as anaphylaxis and similar phenomena are more fully studied. As Fink 

 points out, some of the earlier results are now subject to changed interpretations. It 

 seems unlikely that protein fractions are antigenic, and as Landsteiner' indicates, it 

 is probable that the antigenic property is a function of the size of the molecule. 

 Trypsin digestion destroys the antigenic property of proteins. In consideration of 

 these facts and especially of the anaphylactoid reactions, as well as certain features 

 of the experiments themselves. Wells is doubtful that the results of Abderhalden* with 

 a synthetic polypeptid and of Zunz' with a simpler polypeptid can be accepted. 



Heat or chemicals which render the protein insoluble destroy its sensitizing 

 property, apparently because of the insolubility. Wells points out that the few pro- 

 teins not made insoluble by heat, casein, ovomucoid, so-called "proteoses of plant 



' Starin, W. C: J . Inject. Bis., 23, 139. 1918. 



^ Wells, H. G., and Osborne, T. B.: iUd., 8, 66. 1911. 



JTenBroeck, C: /. Biol. Chem., 17, 369. 1914. 



■• Gaiy, F. P., and Adier, H. M.: /. Med. Research, 13, 433. 1908. 



s Kato, Y.: Miti. a. d. med. Fak. d. k. Univ. Tokyo, 18, 109. 1907. 



^ Fink, E. B.: /. Infect. Dis., 25, 97. 1919. 



'Landsteiner, K.: Biochem. Zlschr., gi, 106. 1919. 



* Abderhalden, E.: Zlschr.f. phys. Chemie, 81, 315. 1912. 



'Zunz, E.: Arch, internat. de physiol., 15, 179, 192. 1919. 



