Non-Sensitizing Protein Antigens.

For certain organ transplantations it has been necessary for us to find two distinct protein antigens toward which dogs may be rendered equally and practically invariably hypersensitive. We have found a very wide variation in canine susceptibility to different proteins, wholly unexpected from our experience with other animal species. The following are typical results:(a) Horse Serum: Dogs injected subcutaneously with 0.5 cc. horse serum per kilogram of body weight, followed 24 hours later by an intravenous injection with the same dose, are almost invariably hypersensitive if tested after an incubation period of about 21 days. Fully 95 per cent of them are thrown into severe anaphylactic shock on intravenous injection with 1 cc. horse serum per kilogram of body weight, with fatalities in about 20 per cent of the cases. With 2 cc. horse serum per kilogram of body weight the fatalities are increased to about 40 per cent.(b) Goat Serum:Dogs injected with the same doses of goat serum and tested after the same incubation period are usually not demonstrably hypersensitive. Only about 30 per cent of them give recognizable anaphylactic reactions on intravenous injection with 2 cc. goat serum per kilogram of body weight.(c) Egg White:Dogs injected with the same doses of 50 per cent egg white (Ringer's solution) and tested after the same incubation period, give no suggestion of anaphylaxis, even on intravenous injection with doses as large as 5 cc. 50 per cent egg white per kilogram of body weight.There is evidently a determining factor in canine protein sensitization of which we are at present wholly ignorant.