198 CHEMISTRY OF THE niMiyiTY REACTIOXS 



pneumoeocci and other bacteria, permitted to autolyze for a proper 

 length of time, produce poisonous substances with all the toxicologic 

 characters of the anaphylatoxin. Too extensive autolysis again de- 

 stroys the poison, which is also produced by digestion of pneumo- 

 eocci with serum from normal guinea-pigs, and more rapidly with 

 serum from sensitized animals, which likewise causes a demonstrably 

 more rapid proteolysis. The pneumococcus anaphylatoxic poison is 

 soluble in ether and seems to be a base, containing amino-acids, but 

 Friedberger did not find anaphylatoxin made from serum proteins to 

 be soluble in ether or alcohol, nor was it precipitated with the globu- 

 lins. The so-called "Abderhalden method" of sero-diagnosis of preg- 

 nancy, which depends on the presence of specific proteolytic properties 

 in the blood, is an especially studied instance of these principles, and 

 is discussed later. 



Presumahly anaphylactic intoxication is hut an exaggeration of the 

 normal process of defense of the body against foreign proteins (in- 

 cluding bacteria) through digestion. Normally this is accomplished 

 in the alimentary tract, and complete disintegration past the toxic 

 stage is made certain by the presence of erepsin in the intestinal wall ; 

 but if intact foreign protein molecules reach the blood in any way, 

 this same digestive destruction is performed by the enzymes of the 

 blood or tissues. So abnormal is the ''parenteral" introduction of 

 foreign proteins that, once it has happened, the protective mechanism 

 is stimulated to the production of large amounts of proteolytic sub- 

 stances, and on this account if another quantity of the same protein 

 is again parenterally introduced the breaking down of the protein is 

 ■extremely rapid. Certain of the disintegration products are toxic, but 

 with the normal rate of disintegration the amount present at any one 

 time is inadequate to cause poisoning ; when the proteolysis is ac- 

 celerated, as in the sensitized animal, a poisonous dose may be pro- 

 duced, with the resulting anaphylactic intoxication.^" Whether this 

 proteolysis takes place both in the blood and tissues is not known. It 

 has been found that the specific proteolytic power of the blood is in- 

 creased in sensitized animals, but on the other liand, there is evidence 

 that without the intervention of the liver (at least in dogs) anaphy- 

 lactic intoxication cannot take place (INlanwaring and others'). During 

 the reaction, in any event, ])i'()du('ts of jirottMii liydi-olysis a])pear in 

 the blood (Abderhalden).'^ 



Among possible cleavage products of proteins which may be the 

 tf)xic agent in anajiliylaxis, is /3-imidazolylethylamine ("histamine"), 

 which is derivable from liistidine, as indicated by the structural for- 

 mulas, and which produces effects resembling acute anaphylactic in- 



17 Heilner (Zeit, Biol., 1012 (58), .S.3.3) bolievos t.liat tlio anaphyhu'tio poisons 

 arc substances wliich normally arc dostroyod by jirotoolysia, but tliat in the 

 sensitized animals there is a depressed catiibolism \\hic]i prcvtMits tlieir destruc- 

 tion. 



18 Zeit. physiol. Chem., 1912 (82), 100. 



