A modified anaphylactic reaction induced by X-rays

The following observations are of interest in connection with a theoretical consideration of the mechanism of classical serum anaphylaxis.

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 sensitized 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 inoculated 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 incubation 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.