972 ANAPHYLAXIS AND ANAPHYLACTOID REACTIONS 



The usual method of sensitization in experimental work is by parenteral intro- 

 duction. In the guinea pig it is usually a single subcutaneous injection. In the dog 

 it may be two or three subcutaneous injections on successive days, or one subcu- 

 taneous injection followed on the next day by an intravenous administration. Intra- 

 peritoneal and intrathecal routes have been employed. If sensitization can occur by 

 way of the intestinal canal, it must presumably be due to absorption of native un- 

 digested protein. Rosenau and Anderson were able to sensitize guinea pigs by feeding 

 horse serum. Van Alstyne and Grant' found that by feeding egg white to dogs the 

 native protein could be identified in blood and urine. Using the method of Prausnitz 

 and KUstner, Walzer and Walzer^ show that the protein of foods to which patients 

 are passively sensitized may be absorbed through the intestine. The practical im- 

 portance of these studies is great, but for quantitative work parenteral routes must be 

 employed. 



For a period of eight to twelve days after the sensitizing dose, subsequent injec- 

 tions of the homologous protein produce no evidence of hypersusceptibility. If during 

 this period a second injection be given, the animal is more likely to become immune 

 than hypersensitive. The sensitiveness usually reaches its height in about twenty-one 

 days, after which it slowly diminishes but probably persists indefinitely. Extremely 

 minute doses seem to delay the appearance of maximum sensitiveness, as is also true 

 of larger doses. Therefore, there is an optimum sensitizing dose which varies in a 

 fairly wide range. 



PASSIVE SENSITIZATION 



The serum (not the cells) of an animal actively sensitized, even before sensitiza- 

 tion in that animal can be satisfactorily demonstrated, or even if that animal be in the 

 temporary refractory state called "anti-anaphylaxis," can produce sensitization upon 

 injection into another animal. This passive sensitization can be demonstrated about 

 four hours after intravenous injection, about twenty-four hours after intraperitoneal 

 injection, and about forty-eight hours after subcutaneous injection, persists for three 

 or four days at its height, and gradually disappears in the course of a few days. If a 

 precipitating serum be prepared in an animal against a certain protein and injected 

 into another animal, the latter becomes sensitive to the homologous protein — a fact 

 pointed out by Doerr and Moldovan.^ Doerr and Russ,'' and Scott,^ have shown that 

 the content of precipitin in the serum employed and the intensity of the anaphylactic 

 shock are generally parallel, but exceptions have been noted by Falk and Caulfield.^ 

 That the young of sensitive female guinea pigs are also hypersensitive is well estab- 

 lished, but it has not been conclusively shown to be by passive sensitization. 



ANAPHYLACTIC SHOCK 



When the homologous protein is injected into the sensitized animal, the reaction 

 is in the form of acute (immediate) or subacute (delayed) shock, depending upon the 

 ' Van Alstyne, E. V. N., and Grant, P. A.: /. Med. Research, 25, 399. 1911-12. 

 * Walzer, A. and M.: Am. J. M. Sc, 173, 279. 1927. 



3 Doerr, R., and Moldovan, J.: Ztschr.f. Immunilatsforsch.u. e.vper. TJierap., 5, 125. 1910. 

 ^ Doerr, R., and Russ, V. K.: ibid., 3, 181. 1909. 

 5 Scott, W. W.: /. Palh. &• Bad., 14, 147. 1910. 

 <> Falk, I. S., and Caulfield, M. F.: loc. cit. 



