192 CHEMISTRY OF THE IMMUNITY REACTIONS 



and a few others, practically any soluble protein will produce sen- 

 sitization and intoxication of susceptible animals, i. e., almost any 

 soluble protein may be an anaphylactogen. As with the other immun- 

 ity reactions, observations have been made which are interpreted as 

 indicating that non-protein substances can produce this reaction, but 

 these interpretations are not generally accepted. (See Antigens, Chap, 

 vii.) It is possible, however, for non-protein substances to combine 

 with or alter the proteins of an animal so that they become as foreign 

 proteins to that animal, and thus cause sensitization; in this way can 

 be explained apparent anaphylactic reactions to iodin and arsenic com- 

 pounds and other non-protein substances.'' As far as my own experi- 

 ments show, nothing less than an entire protein molecule will suffice, 

 the products of protein cleavage all being inactive.^ Zunz^ and Fink,^, 

 however, report some positive results with proteoses. Presumably the 

 inefficiency of gelatin as an anaphylactogen depends upon its de- 

 ficiency in aromatic radicals, since these radicals have been shown 

 (Vaughan, Obermeyer and Pick) to be particularly important in 

 immunological reactions. It is not necessary for a protein to con- 

 tain all the known amino-acids of proteins to be active, however, for 

 certain vegetable proteins (zein, hordein, gliadin) which lack one or 

 more of such amino-acids as glycine, tryptophane, or lysine, pro- 

 duce typical reactions. Some compound proteins arc efficient ana- 

 phylactogens ( mucin, ^^ casein) but with alpha-nucleoproteins which 

 have been thoroughly purified I have obtained only negative results;" 

 as also with histon and nucleic acid, the isolated components of nu- 

 cleins. Globin, from hemoglobin, is also non-antigenic. Bacterial 

 substances, extracts of plant tissues, purified plant proteins, and pro- 

 teins obtained from invertebrates and cold-blooded vertebrates, have 

 all been found to be anaphylactogens, if the}' can be iqt reduced bj^ 

 any means into the blood or tissues in a soluble unaltered condition. 



If the proteins are rendered insoluble bj^ coagulation they become 

 inert, but proteins which cannot be made insoluble bj^ heating [e. g., 

 casein, ovomucoid) withstand boiling temperatures. Trypsin de- 

 stroys anaphylactogens in just the same proportion as it splits the protein 



« See Bottner (Deut. Arch. klin. Med., 1918 (125), 1), concerning collargol 

 anaphylaxis. 



^ Abderhaldcn (Zeit. physiol. Chcin., 1912 (81), 314) states that he has ob- 

 tained a positive reaction with a synthetic polypeptid containing 14 amino-acid 

 molecules, including only leucine and glycocoll. E. Zunz (Jour, physiol. patli. 

 gen., 1917 (17), 449) reports obtaining positive results with much simpler polypop- 

 tids (.■^-5 glycylglycine). These reactions consisted in changes in blood pressure 

 and coagulability in rabbits, and we do not know whether tj'pical shock can be 

 obtained in guinea i)igs with these jxij^tids. 



^7Ainz (ZciL. liniuunit:it., 1913 ((iO), 580). 



"Jour. Infect. J)is., 1919 (25), 97. 



'"Elliott, Jour. Infect. J)is., 1914 (15), 501. 



" See review in Zeit. Irninuniti'lt., 1913 (19), 599, conccriiiiig alpha-nucloopro- 

 tcins, which is the type usually designated as " nucleoproteins." I have found 

 beta-nucleoprotcins to be more effective antigens (Jour, liiol. Chem., 191G (28), 



