992 TECHNIQUE OF EXPERIMENTATION IN ANAPHYLAXIS 



Passive sensitization of guinea pigs may be inhibited and even completely pre- 

 vented by a previous or simultaneous injection .with certain toxic substances, such as 

 foreign serum, foreign or homologous tissue products, and peptone. 



b) Rabbits. — Normal rabbits may be passively sensitized, at times sufficiently 

 to give lethal anaphylaxis, by an intraperitoneal or intravenous injection with a 

 Sufficiently large dose of the serum, defibrinated blood, or whole blood of an actively 

 sensitized or an actively immunized rabbit.' Maximum sensitization is apparently 

 not reached before twenty-four hours. Passive sensitization of rabbits is at times 

 possible with the serum or tissue products of other animal species. Tuberculin hyper- 

 sensitiveness, for example, may be conferred on rabbits by the intraperitoneal injec- 

 tion of muscle juice from tuberculous cattle.^ 



c) Dogs. — Normal dogs may be passively sensitized sufficiently to give recordable 

 anaphylactic reactions, by replacing a third to two-thirds of their total blood volume 

 with the blood of an actively sensitized dog. Slight sensitization is occasionally 

 demonstrable within an hour after this transfusion,^ with maximum sensitization in 

 about twenty-four hours. No suggestion of passive sensitization is demonstrable after 

 fractional transfusion with the blood of a dog actively immunized against the same 

 protein.-* 



d.) Rats — Normal rats weighing at least 80 gm. may be passively sensitized 

 sufficiently to give severe anaphylactic symptoms by the intraperitoneal injection of 

 a sufficiently large dose of rat antiserum. Maximum sensitization is apparently not 

 reached before the forty-eighth hour.^ 



e) Mice. — Schiemann and Meyer'' have recently reported successful passive 

 sensitization of white mice. 



DESENSITIZATION 

 SPECIFIC 



Desensitization of actively or passively sensitized animals may be brought about 

 in all animal species thus far tested by the subcutaneous, intraperitoneal, or intra- 

 venous injection with a sufficiently large dose of the specific foreign protein used in 

 sensitization. Partial desensitization is usually demonstrable within from five to 

 twenty minutes after this injection, with maximum desensitization in from two to 

 three hours. The animal usually remains relatively or completely desensitized for 

 from twenty-four hours to eight days. Kellaway and Cowell, however, report 

 desensitization of guinea pigs lasting thirty days.^ 



The minimum desensitizing dose varies with the age of the animal and the method 

 of sensitization.* Complete desensitization of horse-serum-sensitized guinea pigs, for 

 example, is usually brought about by the subcutaneous injection of o.oi-cc. horse 

 serum. Occasionally, however, i-cc. horse serum produces only partial desensitiza- 

 tion. 



• Arthus, M.: Arch, internal, de physiol., 15, 164. 1919. 



^ Granucci, L.: Clin, vet., 42, 115. 1919. 



3 Manwaring, W. H. : loc. cil. 



iManwaring, W. H., Wright, R. W., and Shumaker, P. W.: J. A.M. A., 86, 1271. 1926. 



5 Parker, J. T. and F.: loc. cil. ' Kellaway, C. H., and Cowell, S. J.: loc. cit. 



'' Schiemann, O., and Meyer, H.: loc. cit. * Thomson, O.: loc. cit. 



