no Immunity 



Experimental study shows that when an animal is injected with 

 an alien protein- of almost any kind, a reaction takes place that 

 usually is not completed under six days. If a second injection is 

 given before the reaction is perfected, the mechanism of immunity is 

 set in action, and the animal proceeds to defend itself through the 

 various means described. If the second administration be deferred, 

 however, until the first reaction is completed, it seems to find the 

 animal in a state of disturbed biologic equihbrium, the nature of 

 which is not understood, but which is characterized by a profound 

 disturbance that may terminate in death. The reaction is quite 

 specific; the sensitization, once effected, may continue throughout 

 the remainder of the life of the animal and be transmitted from the 

 mother to her offspring through her blood. The reaction can be 

 brought about by feeding the protein or by injecting it. It has an 

 important bearing upon infection and immunity, the chief example 

 being seen in the tuberculin reaction. 



The symptomatology of anaphylaxis is interesting and char- 

 acteristic. When it is desirable to study it, a guinea-pig is first 

 given a sensitizing dose of horse-serum. This may be very small. 

 Rosenau and Anderson found one guinea-pig to be sensitized by 

 one-millionth of a cubic centimeter. In most of their work they used 

 less than M50 cc. It is necessary to wait until the effects of this 

 first injection are completely over before giving the poisoning dose. 

 This period of incubation lasts about twelve days. After the lapse 

 of this time, the second dose, usually about J^o cc, is given. Both 

 doses are given by injection into the peritoneal cavity. 



The symptoms come on almost immediately after the second 

 dose. The animal is profoundly depressed, extremely uneasy, pants 

 for breath, and suffers from intense itching of the face. It soon 

 . falls, continues to gasp for breath, and dies within an hour. The 

 disturbances in the body of the animal are sufficient to account for 

 the symptoms. Extensive lesions exist, the first to be described 

 by Rosenau* affecting the mucous membrane of the stomach, which 

 appeared ecchymotic and ulcerated. Gay and Southardf found 

 hemorrhages in most of the organs, and believe anaphylaxis to 

 depend upon the presence, in the blood of the sensitized animal, of 

 a substance to which they have given the name anaphylactin. 

 Besredka and Steinhardtf found that by the repeated injection of 

 horse-serum into guinea-pigs, the intervals being too short to permit 

 anaphylaxis, antianaphylactin could be prepared. It seems difficult, 

 however, to imagine how such a substance could remain in the blood 

 throughout the entire subsequent life of the animal. 



Vaughan has endeavored to explain anaphylaxis by assum- 

 ing that when the strange protein in the blood reaches the cells 



*"Bull. No. 32 of the Hygienic Laboratory," Washington, D. C, October, 

 1906. 



t "Jour. Med. Research," July, 1908, xrx, No. i, pp. i, 5, 17. 



t "Ann. de I'Inst. Pasteur," February 25, 1907, xxi. No. 2, pp. 117-127. 



