Anaphylactic Reaction Induced by X-Rays. 23 



We have found it possible, as has v. Heinrich also, to modify 

 the manifestations of anaphylaxis in guinea pigs by exposing them 

 to X-rays. Guinea pigs weighing about 250 grams were given 

 an intraperitoneal inoculation of 0.1 c.c. of horse serum (1 c.c. of a 

 1 — 10 dilution) for sensitization. Half of the number of sen- 

 sitized animals were radiated immediately and then each day 

 thereafter for 10 days. The X-rays were delivered from a Coolidge 

 tube governed by a spark gap of 3 inches with 10 milliamperes of 

 current. The distance from the anode to the surface of the 

 animal's body was 6 inches and the total time of exposure was 10 

 minutes. 



14 days after sensitization 0.1 c.c. or 0.01 c.c. of horse serum 

 was inoculated into the jugular vein as an intoxicating dose. In 

 the animals sensitized but not X-rayed, typical anaphylactic 

 manifestations and usually acute death followed the inoculation 

 with either amount of antigen. The X-rayed animals, on the 

 other hand, showed either very slight or no objective anaphylactic 

 manifestations. If, however, 4 weeks were allowed to elapse from 

 the time of sensitization, then a similar amount of antigen inoc- 

 ulated intravenously, there was no difference in the behavior of 

 X-rayed animals as compared with the controls. Further, it 

 was found that radiation at any time other than during the incuba- 

 tion period did not induce a modified reaction. 



With these facts established, we directed our attention to a 

 study of the anaphylactic state of isolated tissue. It may be 

 said that many investigators describe the anaphylactic reaction of 

 isolated smooth muscle as an index of the reaction of the animal 

 body as a whole. Indeed, this phenomenon is regarded by them 

 as the most important evidence which indicates that the locus of 

 antigen-antibody union is intracellular. 



Female guinea pigs of about 225 grams were sensitized by an 

 intrapleural inoculation of 0.1 c.c. of horse serum and subsequently 

 treated as described in the original experiment. At intervals of 14 

 and 30 days following sensitization, the horns of the uteri were re- 

 moved and segments of these treated in accordance with the 

 principles of the well-known Dale method for studying the physi- 

 ological behavior of isolated tissues. For each tissue preparation, 

 we employed a suspension bath of 250 c.c. of oxygenated Locke's 



